Aldehyde Dehydrogenase Superfamily Research Articles

Comprehensive analysis of Brassica napus aldehyde dehydrogenase superfamily genes and demonstration of BnALDH7B2 in clubroot resistance

Oilseed rapa (Brassica napus), an important oil crop worldwide, is often threatened by various adversity stresses, especially Plasmodiophora brassicae, resulting in abnormal growth and decreased yield. The aldehyde dehydrogenase (ALDH) family is crucial for plant growth and environmental stress adaptations. Nevertheless, BnALDH members and their responses to P. brassicae are unclear in B. napus. Here, 53 B. napus ALDH members were identified and classified into 10 subfamilies. Collinearity analyses revealed that the BnALDHs gene family primarily underwent expansion through segmental duplication. Structural analyses illustrated that the BnALDHs in each specific subfamily were relatively conserved. Analysis of cis-elements in BnALDH promoter regions revealed the presence of multiple elements related to stress response and plant hormones. Transcriptome analyses indicated that BnALDHs were expressed throughout B. napus multiple tissues and growth stages. Most BnALDHs were differentially expressed under different stress treatments, with BnALDH7B2 significantly upregulated during P. brassicae stress. In addition, the BnALDH7B2 overexpression transgenic plants conferred tolerance to P. brassicae stress. Molecular docking results showed that BnALDH7B2 was more functionally dependent on NAD+ than on NADP+, while phenylacetaldehyde, benzaldehyde, trans-2-nonenal, α-aminoadipate-semialdehyde, and 4-guanidinobutyraldehyde could potentially be used as substrates for BnALDH7B2. The results provide insights into the function of BnALDHs in B. napus, serving as a baseline for identifying the functional role of BnALDH7B2 under P. brassicae stress.

Genome-wide identification, characterization and evolutionary analysis of betaine aldehyde dehydrogenase (BADH), mitogen-activated protein kinase (MAPK) and sodium/hydrogen exchanger (NHX) genes in maize (Zea mays) under salt stress

AbstractBetaine aldehyde dehydrogenase (BADH), mitogen-activated protein kinase (MAPK) and sodium/hydrogen exchanger (NHX) play important roles in the response to salt stress. This is the first study to identify the BADH and NHX genes in maize (Zea mays) via genome-wide analysis. The qRT‒PCR results indicated that ZmNHX was upregulated by 4.38-fold, while a significant difference was not observed in ZmBADH or ZmMAPK, with fold changes of 0.96 and 1.06, respectively, under salinity stress. Genome-wide analysis revealed 8 ZmBADH, 19 ZmMAPK and 11 ZmNHX proteins in Z. mays. Domain analysis confirmed the presence of the aldehyde dehydrogenase superfamily (ALDH-SF), protein kinase and Na_H_Exchanger domains in the ZmBADH, ZmMAPK and ZmNHX proteins, respectively. Motif analysis indicated that the phylogenetic relationships were similar to the conserved motif distributions within the clade. The Ka/Ks ratio indicated that the ZmBADH, ZmMAPK and ZmNHX genes were influenced primarily by purifying selection. This study provides comprehensive identification, characterization, and evolutionary analysis for a better understanding of the ZmBADH, ZmMAPK and ZmNHX genes in maize.

Aldehyde Dehydrogenase Diversity in Azospirillum Genomes

Aldehyde dehydrogenases (ALDHs) are indispensable enzymes that play a pivotal role in mitigating aldehyde toxicity by converting them into less reactive compounds. Despite the availability of fully sequenced Azospirillum genomes in public databases, a comprehensive analysis of the ALDH superfamily within these genomes has yet to be undertaken. This study presents the identification and classification of 17 families and 31 subfamilies of ALDHs in fully assembled Azospirillum genomes. This classification system framework provides a more comprehensive understanding of the diversity and redundancy of ALDHs across bacterial genomes, which can aid in elucidating the distinct characteristics and functions of each family. The study also proposes the adoption of the ALDH19 family as a powerful phylogenetic marker due to its remarkable conservation and non-redundancy across various Azospirillum species. The diversity of ALDHs among different strains of Azospirillum can influence their adaptation and survival under various environmental conditions. The findings of this study could potentially be used to improve agricultural production by enhancing the growth and productivity of crops. Azospirillum bacteria establish a mutualistic relationship with plants and can promote plant growth by producing phytohormones such as indole-3-acetic acid (IAA). The diversity of ALDHs in Azospirillum can affect their ability to produce IAA and other beneficial compounds that promote plant growth and can be used as biofertilizers to enhance agricultural productivity.

Genome-wide characterization and gene expression analyses of ALDH gene family in response to drought stress in moso bamboo (Phyllostachys edulis)

Aldehyde dehydrogenase (ALDH) superfamily, comprising enzymes dependent on NAD+ or NADP+, plays an important role in controlling plant growth and development, as well as in responsing to phytohormone and environmental stress. These enzymes possess the ability to prevent toxic effects of aldehydes by converting them into their corresponding carboxylic acids. However, the potential function of ALDH genes in moso bamboo (Phyllostachys edulis) remains largely unknown. In this study, the ALDH gene superfamily in moso bamboo was analyzed through genome-wide screening, the evolutionary relationship of expansion genes was conducted. Tissue-specific expression patterns of ALDH genes were observed in 26 different tissues. Plant hormone and environmental stress responsive cis-elements were identified in the promoter of ALDH genes, which were supported by public databases data on the expression patterns under various abiotic stresses and hormone treatments. ALDH activity was increased in moso bamboo seedlings exposed to drought, compared to control condition. Furthermore, PeALDH2B2 was found to physically interact with PeGPB1 in response to drought. Overall, the study provides a comprehensive analysis of the ALDH family in moso bamboo and contributes to our understanding of the function of ALDH genes in growth, development, and adaptation to drought stresses.

Identification and characterization of aldehyde dehydrogenase (ALDH) gene superfamily in garlic and expression profiling in response to drought, salinity, and ABA

In response to biotic and abiotic stressors, aldehydes are detoxified and converted to carboxylic acids by aldehyde dehydrogenases (ALDHs), which are enzymes that use NAD+/NADP+ as cofactors. Garlic (Allium sativum L.) has not yet undergone a systematic examination of the ALDH superfamily, despite the genome sequence having been made public. In this investigation, we identified, characterized, and profiled the expression of the garlic ALDH gene family over the entire genome. The ALDH Gene Nomenclature Committee (AGNC) classification was used to classify and name the 34 ALDH genes that were discovered. Except for chromosome 8, all AsALDH genes were dispersed across the chromosomes. AsALDH genes have various localizations, according to predictions about subcellular localization. The AsALDH proteins are more varied and closely related to rice than to Arabidopsis, according to a study of conserved motifs and phylogenetic relationships. The presence of stress modulation pathways is indicated by the abundance of stress-related cis-elements in the AsALDH genes' promoter regions. Analysis of the RNA-seq data showed that AsALDHs expressed differently in various tissues and at various developmental stages. Nine AsALDHs were chosen for study using RT-qPCR, and the results revealed that the majority of the genes were upregulated in response to ABA and downregulated in response to salinity and drought. The results of this study improved our knowledge of the traits, evolutionary background, and biological functions of AsALDHs genes in growth and development.

Mechanistic roles of the neighbouring cysteine in enhancing nucleophilicity of catalytic residue in a two-cysteine succinic semialdehyde dehydrogenase.

Succinic semialdehyde dehydrogenase (SSADH) catalyses the conversion of succinic semialdehyde into succinic acid and two electrons are transferred to NAD(P)+ to yield NAD(P)H. Our previous work has already reported the catalytic role of Cys289 of two-cysteine SSADH from Acinetobacter baumannii (AbSSADH). However, the mechanistic role of the neighbouring conserved Cys291 and Glu255 remains unexplored. In this study, the functional roles of Cys291 and Glu255 in AbSSADH catalysis have been characterized. Results demonstrated that the E255A activity was almost completely lost, ~ 7000-fold lower than the wild-type (WT), indicating that Glu255 is very crucial and directly involved in AbSSADH catalysis. However, the C291A and C291S variants activity and catalytic turnover (kcat ) decreased ~ 2-fold and 9-fold respectively. To further characterize the functional roles of Cys291, we employed two pH-dependent methods; pre-steady-state burst amplitude and NADP-enzyme adduct formation. The results showed that the pKa values of catalytic Cys289 measured for the WT and C291A reactions were 7.8 and 8.7-8.8, respectively, suggesting that Cys291 can lower the pKa of Cys289 and consequently trigger the deprotonation of a Cys289 thiol. In addition, the Cys291 also plays a role in disulfide/sulfhydryl redox regulation for AbSSADH activity. Hence, we demonstrated for the first time the dual functions of Cys291 in enhancing the nucleophilicity of the catalytic Cys289 and regulating a disulfide/sulfhydryl redox switch for AbSSADH catalysis. The mechanistic insights into the nucleophilicity enhancement of the catalytic cysteine of AbSSADH might be applicable to understanding how the microenvironment increases cysteine reactivity in other enzymes in the aldehyde dehydrogenase superfamily.

Aldehyde dehydrogenase superfamily in sorghum: genome-wide identification, evolution, and transcript profiling during development stages and stress conditions

BackgroundAldehyde dehydrogenases (ALDHs) are a family of NAD(P)+ dependent enzymes that detoxify aldehydes by promoting their oxidation to respective carboxylic acids. The role of ALDH enzymes in various plant species has been extensively studied, revealing their critical role in salinity, drought, heat, and heavy metal stress tolerance. Despite their physiological significance, ALDH genes in Sorghum bicolor have yet to be studied thoroughly.ResultsIn this study, a total of 19 ALDH genes have been identified that have been grouped into ten families based on the criteria of the ALDH gene nomenclature committee. Segmental duplication assisted more in the enhancement of SbALDH gene family members than tandem duplication. All the identified SbALDH members made a cluster with monocot rice and maize in the phylogenetic tree rather than dicot species, suggesting the pre-eudicot-monocot separation of the ALDH superfamily members. The gene structure and protein domain were found to be mostly conserved in separate phylogenetic classes, indicating that each family played an important role in evolution. Expression analysis revealed that several SbALDHs were expressed in various tissues, developmental stages, and in response to abiotic stresses, indicating that they can play roles in plant growth, development, or stress adaptation. Interestingly, the majority of the SbALDH genes were found to be highly responsive to drought stress, and the SbALDH18B1 transcript showed maximum enhancement in all the stress conditions. The presence of cis-acting elements (mainly ABRE and MBS) in the promoter region of these genes might have a significant role in drought tolerance.ConclusionsOur findings add to the current understanding, evolutionary history, and contribution of SbALDHs in stress tolerance, and smooth the path of further functional validation of these genes.

Deletion of Aldh4a1 Leads to Impaired Sperm Maturation in Mice

ALDH4A1, a member of the aldehyde dehydrogenase superfamily, is a key enzyme in the mitochondrial proline metabolism pathway. Recent studies have shown that mutations in aldh4a1 lead to reduced fertility and reproductive premature aging of male nematodes. However, the effect of ALDH4A1 on fertility of male mice has not been studied. In this study, we used CRISPR-Cas9 technology to construct a knockout mouse model of Aldh4a1 for the first time to explore the effect of this gene on the reproduction of male mice. The results showed that compared with WT male mice, Aldh4a1^(-/-) male mice were fertile, had normal spermatogenesis but defect in sperm maturation in the epididymis documented by impaired motility, increased morphological abnormalities and increased spontaneous acrosome reaction. In addition, transmission electron microscopy showed vacuoles in the sperm mitochondria, and fracture in the neck of sperms and vacuoles in these mice. These results revealed that ALDH4A1 plays a vital role in the structure of sperm flagellum and the process of sperm maturation in mice.

Expression, purification and crystallization of a novel metagenome-derived salicylaldehyde dehydrogenase from Alpine soil.

Salicylaldehyde dehydrogenase (SALD) catalyses the last reaction in the upper pathway of naphthalene degradation: the oxidation of salicylaldehyde to salicylate. This enzyme has been isolated and studied from a few organisms that belong to the betaproteobacteria and gammaproteobacteria, predominantly Pseudomonas putida. Furthermore, there is only one crystal structure of this enzyme, which was obtained from P. putida G7. Here, crystallographic studies and analysis of the crystal structure of an Alpine soil metagenome-derived SALD (SALDAP) from an alphaproteobacterium are presented. The SALDAP gene was discovered using gene-targeted sequence assembly and it was cloned into a pLATE51 vector. The recombinant protein was overexpressed in Escherichia coli BL21 (DE3) cells and the soluble protein was purified to homogeneity. The protein crystallized at 20°C and diffraction data from the crystals were collected at a resolution of 1.9 Å. The crystal belonged to the orthorhombic space group C2221, with unit-cell parameters a = 116.8, b = 121.7, c= 318.0 Å. Analysis of the crystal structure revealed its conformation to be similar to the organization of the aldehyde dehydrogenase superfamily with three domains: the catalytic, NAD+-binding and bridging domains. The crystal structure of NahF from P.putida G7 was found to be the best structural homologue of SALDAP, even though the enzymes share only 48% amino-acid identity. Interestingly, a carboxylic acid (protocatechuic acid) was found to be a putative ligand of the enzyme and differential scanning fluorimetry was employed to confirm ligand binding. These findings open up the possibility of studying the mechanism(s) of product inhibition and biocatalysis of carboxylic acids using this enzyme and other related aldehyde dehydrogenases.

A comprehensive survey of the aldehyde dehydrogenase gene superfamily in Saccharum and the role of ScALDH2B-1 in the stress response

Aldehyde dehydrogenases (ALDHs) belong to NAD(P) + -dependent enzymes and are considered ‘‘aldehyde scavengers’’. They play crucial roles in growth, development, and environmental stress adaptation in plants. In this study, a total of 70 SsALDH and 14 ShALDH superfamily genes were identified in Saccharum spontaneum and Saccharum spp. R570 cultivar, respectively. Results showed that the SsALDH superfamily was classified into 10 ALDH families, and the ShALDH superfamily was divided into eight ALDH families. A co-expression network analysis suggested that these ALDH proteins may play vital roles in the stress response due to the fact that they are involved in the metabolism of proline, γ-aminobutyrate, and lysine. The promotor cis- element prediction revealed that the ALDH genes may be regulated by many phytohormones and are involved in various stress responses. RNA-seq data and qRT-PCR analysis inferred that ALDH genes in Saccharum played various roles in response to drought, cold and Sporisorium scitamineum stresses, and they were constitutively expressed in different sugarcane tissues. Additionally, an expression analysis of ScALDH2B-1 suggested significant changes under various stresses. The prokaryotic expression of ScALDH2B-1 in Escherichia coli BL21 cells resulted in enhanced tolerance to salinity. The ectopic expression of ScALDH2B-1 in Nicotiana benthamiana showed that, after challenged by Fusarium solani var. coeruleum, several HR maker genes were upregulated, while the accumulation of H 2 O 2 and HR-like cell death were triggered. A working model of the function of ALDHs in the Saccharum species was thus proposed. This study contributes to our understanding of the evolution and function of ALDH superfamily genes in Saccharum , and it also provides a baseline for the function identification of ScALDH2B-1 under biotic stress. • Totally, 70 SsALDH and 14 ShALDH were identified in Saccharum spontaneum and Saccharum spp. R570 cultivar, respectively. • SsALDH superfamily was classified into ten ALDH families and ShALDH superfamily was divided into eight ALDH families. • Co-expression network indicated that ALDH proteins involved in the metabolism of proline, γ-aminobutyrate, and lysine. • Promotor cis -element and expression profiles analysis suggested that ALDHs may play vital roles under various stresses. • The function analysis of ScALDH2B-1 showed it might play an important role under various abiotic and biotic stimuli.

The tetrameric assembly of 2-aminomuconic 6-semialdehyde dehydrogenase is a functional requirement of cofactor NAD+ binding.

The bacterium Pseudomonas sp. AP-3 is able to use the environmental pollutant 2-aminophenol as its sole source of carbon, nitrogen, and energy. Eight genes (amnA, B, C, D, E, F, G, and H) encoding 2-aminophenol metabolizing enzymes are clustered into a single operon. 2-Aminomuconic 6-semialdehyde dehydrogenase (AmnC), a member of the aldehyde dehydrogenase (ALDH) superfamily, is responsible for oxidizing 2-aminomuconic 6-semialdehyde to 2-aminomuconate. In contrast to many other members of the ALDH superfamily, the structural basis of the catalytic activity of AmnC remains elusive. Here, we present the crystal structure of AmnC, which displays a homotetrameric quaternary assembly that is directly involved in its enzymatic activity. The tetrameric state of AmnC in solution was also presented using small-angle X-ray scattering. The tetramerization of AmnC is mediated by the assembly of a protruding hydrophobic beta-strand motif and residues V121 and S123 located in the NAD+ -binding domain of each subunit. Dimeric mutants of AmnC dramatically lose NAD+ binding affinity and failed to oxidize the substrate analogue 2-hydroxymuconate-6-semialdehyde to α-hydroxymuconic acid, indicating that tetrameric assembly of AmnC is functional requirement.

Aldehyde Dehydrogenase 3 Is an Expanded Gene Family with Potential Adaptive Roles in Chickpea.

Legumes play an important role in ensuring food security, improving nutrition and enhancing ecosystem resilience. Chickpea is a globally important grain legume adapted to semi-arid regions under rain-fed conditions. A growing body of research shows that aldehyde dehydrogenases (ALDHs) represent a gene class with promising potential for plant adaptation improvement. Aldehyde dehydrogenases constitute a superfamily of proteins with important functions as ‘aldehyde scavengers’ by detoxifying aldehydes molecules, and thus play important roles in stress responses. We performed a comprehensive study of the ALDH superfamily in the chickpea genome and identified 27 unique ALDH loci. Most chickpea ALDHs originated from duplication events and the ALDH3 gene family was noticeably expanded. Based on the physical locations of genes and sequence similarities, our results suggest that segmental duplication is a major driving force in the expansion of the ALDH family. Supported by expression data, the findings of this study offer new potential target genes for improving stress tolerance in chickpea that will be useful for breeding programs.

Genome-wide identification, evolution, and transcript profiling of Aldehyde dehydrogenase superfamily in potato during development stages and stress conditions

The Aldehyde dehydrogenase (ALDH) superfamily comprises a group of enzymes involved in the scavenging of toxic aldehyde molecules by converting them into their corresponding non-toxic carboxylic acids. A genome-wide study in potato identified a total of 22 ALDH genes grouped into ten families that are presented unevenly throughout all the 12 chromosomes. Based on the evolutionary analysis of ALDH proteins from different plant species, ALDH2 and ALDH3 were found to be the most abundant families in the plant, while ALDH18 was found to be the most distantly related one. Gene expression analysis revealed that the expression of StALDH genes is highly tissue-specific and divergent in various abiotic, biotic, and hormonal treatments. Structural modelling and functional analysis of selected StALDH members revealed conservancy in their secondary structures and cofactor binding sites. Taken together, our findings provide comprehensive information on the ALDH gene family in potato that will help in developing a framework for further functional studies.

The plant pathogen enzyme AldC is a long‐chain aliphatic aldehyde dehydrogenase

Aldehyde dehydrogenases are versatile enzymes that serve a range of biochemical functions. Although traditionally considered metabolic housekeeping enzymes because of their ability to detoxify reactive aldehydes, like those generated from lipid peroxidation damage, the contributions of these enzymes to other biological processes are widespread. For example, the plant pathogen Pseudomonas syringae strain PtoDC3000 uses an indole-3-acetaldehyde dehydrogenase to synthesize the phytohormone indole-3-acetic acid to elude host responses. Here we investigate the biochemical function of AldC from PtoDC3000. Analysis of the substrate profile of AldC suggests that this enzyme functions as a long-chain aliphatic aldehyde dehydrogenase. The 2.5 Å resolution X-ray crystal of the AldC C291A mutant in a dead-end complex with octanal and NAD+ reveals an apolar binding site primed for aliphatic aldehyde substrate recognition. Functional characterization of site-directed mutants targeting the substrate- and NAD(H)-binding sites identifies key residues in the active site for ligand interactions, including those in the “aromatic box” that define the aldehyde-binding site. Overall, this study provides molecular insight for understanding the evolution of the prokaryotic aldehyde dehydrogenase superfamily and their diversity of function.

The plant pathogen enzyme AldC is a long-chain aliphatic aldehyde dehydrogenase

Aldehyde dehydrogenases are versatile enzymes that serve a range of biochemical functions. Although traditionally considered metabolic housekeeping enzymes because of their ability to detoxify reactive aldehydes, like those generated from lipid peroxidation damage, the contributions of these enzymes to other biological processes are widespread. For example, the plant pathogen Pseudomonas syringae strain PtoDC3000 uses an indole-3-acetaldehyde dehydrogenase to synthesize the phytohormone indole-3-acetic acid to elude host responses. Here we investigate the biochemical function of AldC from PtoDC3000. Analysis of the substrate profile of AldC suggests that this enzyme functions as a long-chain aliphatic aldehyde dehydrogenase. The 2.5 Å resolution X-ray crystal of the AldC C291A mutant in a dead-end complex with octanal and NAD+ reveals an apolar binding site primed for aliphatic aldehyde substrate recognition. Functional characterization of site-directed mutants targeting the substrate- and NAD(H)-binding sites identifies key residues in the active site for ligand interactions, including those in the "aromatic box" that define the aldehyde-binding site. Overall, this study provides molecular insight for understanding the evolution of the prokaryotic aldehyde dehydrogenase superfamily and their diversity of function.

Genome-wide characterization of ALDH Superfamily in Brassica rapa and enhancement of stress tolerance in heterologous hosts by BrALDH7B2 expression

Aldehyde dehydrogenase (ALDH) carries out oxidation of toxic aldehydes using NAD+/NADP+ as cofactors. In the present study, we performed a genome-wide identification and expression analysis of genes in the ALDH gene family in Brassica rapa. A total of 23 ALDH genes in the superfamily have been identified according to the classification of ALDH Gene Nomenclature Committee (AGNC). They were distributed unevenly across all 10 chromosomes. All the 23 Brassica rapa ALDH (BrALDH) genes exhibited varied expression patterns during treatments with abiotic stress inducers and hormonal treatments. The relative expression profiles of ALDH genes in B. rapa showed that they are predominantly expressed in leaves and stem suggesting their function in the vegetative tissues. BrALDH7B2 showed a strong response to abiotic stress and hormonal treatments as compared to other ALDH genes; therefore, it was overexpressed in heterologous hosts, E. coli and yeast to study its possible function under abiotic stress conditions. Over-expression of BrALDH7B2 in heterologous systems, E. coli and yeast cells conferred significant tolerance to abiotic stress treatments. Results from this work demonstrate that BrALDH genes are a promising and untapped genetic resource for crop improvement and could be deployed further in the development of drought and salinity tolerance in B. rapa and other economically important crops.

Evolutionary, Functional and Structural Studies of the ALDH27 Enzymes

The ALDH27 family of the aldehyde dehydrogenase superfamily comprises bacterial enzymes poorly studied so far in spite of seemingly being widely distributed, and of their putative important metabolic roles. With the double aim of exploring their occurrence within bacteria and investigating their physiological functions, we performed comprehensive phylogenetic and genomic context analyses. We also biochemically and structurally characterized the three ALDH27 enzymes present in Pseudomonas aeruginosa PAO1 and tested the growth of PAO1 mutant strains on compounds that produce the putative substrate aldehydes. We retrieved 245 non‐redundant ALDH27 sequences from 149 reference genomes, most of them from αβγ‐proteobacteria, some from actinobacteria and a few from firmicutes. These sequences formed two subfamilies: ALDH27A and ALDH27B, which in turn consists of three clades. The neighboring gene of the aldh27A locus is a class I aldolase not characterized so far. Therefore, we could not infer the physiological role of these enzymes from their genomic context. The genomic contexts of the aldh27B1 and aldh27B3 are consistent with their participation in polyamines catabolism. In the neighborhood of the aldh27B2 locus there are genes encoding for either histamine dehydrogenase or histamine‐pyruvate aminotransferase, suggesting their involvement in histamine catabolism. The in vitro and in vivo specificity of PA5312, which belongs to the ALDH27B3 clade, confirmed that it is essential for the catabolism of agmatine, putrescine, cadaverine, spermine, spermidine, and diaminopropane. Similar studies showed that PA0219, which belongs to the ALDH27B2 clade, is essential for the catabolism of histamine. PA4189, which belongs to the ALDH27A subfamily, oxidizes most of the aminoaldehydes substrates of PA5312 and PA0219 enzymes, but they are not its physiological substrates as the PAO1 mutant strain lacking PA4189 activity grew in polyamines or histamine. To find out the structural basis of aldehyde specificity, we obtained the three‐dimensional structures of PA4189 and PA5312 by X‐ray crystallography and performed docking simulations with aldehydes that in vitro are substrates of these enzymes. Then, we examined the conservation within each subfamily and clade of the active site residues in critical positions, and found highly conserved acidic residues, aspartate or glutamate, which may be important for binding the aldehyde substrate. Together, our results provide insights into the diversification of the ALDH27 family in bacteria and of the physiological functions of the members of this family.Support or Funding InformationFinancially supported by DGAPA‐UNAM (PAPIIT IN220317) and CONACYT 283524 grants to RAMC, and DGAPA‐UNAM (PAPIIT IN218819) grant to HRR. ALJV is a recipient of a postdoctoral scholarship from DGAPA‐UNAM and YVCC of a doctoral scholarship from CONACYT.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Expression, purification and crystallization of the novel Xenopus tropicalis ALDH16B1, a homologue of human ALDH16A1

ALDH16 is a novel family of the aldehyde dehydrogenase (ALDH) superfamily with unique structural characteristics that distinguish it from the other ALDH superfamily members. In addition to structural characteristics, there is an evolutionary-related grouping within the ALDH 16 genes. The ALDH16 isozymes in frog, lower animals, and bacteria possess a critical Cys residue in their active site, which is absent from ALDH16 in mammals and fish. Genomic analysis and plasma metabolomic studies have associated ALDH16A1 with the pathogenesis of gout in humans, although its actual involvement in this disease is poorly understood. Insight into the structure of ALDH16A1 is an important step in deciphering its function in gout. Herein, we report our efforts towards the structural characterization of Xenopus tropicalis ALDH16B1 (the homolog of human ALDH16A1) that was predicted to be catalytically-active. Recombinant ALDH16B1 was expressed in Sf9 cells and purified using affinity and size exclusion chromatography. Crystallization of ALDH16B1 was achieved by vapor diffusion. A data set was collected at 2.5 Å and preliminary crystallographic analysis showed that the frog ALDH16B1 crystals belong to the P 212 121 space group with unit cell parameters a = 80.48 Å, b = 89.73 Å, c = 190.92 Å, α = β = γ = 90.00°. Structure determination is currently in progress.

Biostimulation potentials of corn steep liquor in enhanced hydrocarbon degradation in chronically polluted soil.

The effects of corn steep liquor (CSL) on hydrocarbon degradation and microbial community structure and function was evaluated in field-moist soil microcosms. Chronically polluted soil treated with CSL (AB4) and an untreated control (3S) was compared over a period of 6weeks. Gas chromatographic fingerprints of residual hydrocarbons revealed removal of 95.95% and 94.60% aliphatic and aromatic hydrocarbon fractions in AB4 system with complete disappearance of nC1-nC8, nC10, nC15, nC20-nC23 aliphatics and aromatics such as naphthalene, acenaphthylene, fluorene, phenanthrene, pyrene, benzo(a)anthracene, and indeno(123-cd)pyrene in 42days. In 3S system, there is removal of 61.27% and 66.58% aliphatic and aromatic fractions with complete disappearance of nC2 and nC21 aliphatics and naphthalene, acenaphthylene, fluorene, phenanthrene, pyrene, and benzo(a)anthracene aromatics in 42 days. Illumina shotgun sequencing of the DNA extracted from the two systems showed the preponderance of Actinobacteria (31.46%) and Proteobacteria (38.95%) phyla in 3S and AB4 with the dominance of Verticillium (22.88%) and Microbacterium (8.16%) in 3S, and Laceyella (24.23%), Methylosinus (8.93%) and Pedobacter (7.73%) in AB4. Functional characterization of the metagenomic reads revealed diverse metabolic potentials and adaptive traits of the microbial communities in the two systems to various environmental stressors. It also revealed the exclusive detection of catabolic enzymes in AB4 system belonging to the aldehyde dehydrogenase superfamily. The results obtained in this study showed that CSL is a potential resource for bioremediation of hydrocarbon-polluted soils.

Structural and Biochemical Characterization of Aldehyde Dehydrogenase 12, the Last Enzyme of Proline Catabolism in Plants

Heterokonts, Alveolata protists, green algae from Charophyta and Chlorophyta divisions, and all Embryophyta plants possess an aldehyde dehydrogenase (ALDH) gene named ALDH12. Here, we provide a biochemical characterization of two ALDH12 family members from the lower plant Physcomitrella patens and higher plant Zea mays. We show that ALDH12 encodes an NAD+-dependent glutamate γ-semialdehyde dehydrogenase (GSALDH), which irreversibly converts glutamate γ-semialdehyde (GSAL), a mitochondrial intermediate of the proline and arginine catabolism, to glutamate. Sedimentation equilibrium and small-angle X-ray scattering analyses reveal that in solution both plant GSALDHs exist as equilibrium between a domain-swapped dimer and the dimer-of-dimers tetramer. Plant GSALDHs share very low-sequence identity with bacterial, fungal, and animal GSALDHs (classified as ALDH4), which are the closest related ALDH superfamily members. Nevertheless, the crystal structure of ZmALDH12 at 2.2-Å resolution shows that nearly all key residues involved in the recognition of GSAL are identical to those in ALDH4, indicating a close functional relationship with ALDH4. Phylogenetic analysis suggests that the transition from ALDH4 to ALDH12 occurred during the evolution of the endosymbiotic plant ancestor, prior to the evolution of green algae and land plants. Finally, ALDH12 expression in maize and moss is downregulated in response to salt and drought stresses, possibly to maintain proline levels. Taken together, these results provide molecular insight into the biological roles of the plant ALDH12 family.