N-terminal Amino Acid Residues Research Articles

Designed Streptococcus pyogenes Sortase A Accepts Branched Amines as Nucleophiles in Sortagging.

Sortase-mediated ligation (sortagging) is commonly performed using the Staphylococcus aureus sortase A (SaSrtA) that strictly recognizes the N-terminal glycine residue. In this work, a rational design of Streptococcus pyogenes sortase A (SpSrtA) for improved transpeptidase activity toward different N-terminal amino acid residues was conducted. The generated variant SpSrtA M3 (E189H/V206I/E215A) showed up to 6.6-fold (vs SpSrtA wild-type) enhanced catalytic efficiency. Additionally, M3 retains the specificity toward N-terminal alanine, glycine, serine residues, as well as branched (at α-carbon) primary amines as wild-type parent. Furthermore, M3 was applied for head-to-tail backbone cyclization of proteins.

Antibiofilm Activity of Acidic Phospholipase Isoform Isolated from Bothrops erythromelas Snake Venom.

Introduction: Bacterial resistance is a worldwide public health problem, requiring new therapeutic options. An alternative approach to this problem is the use of animal toxins isolated from snake venom, such as phospholipases A2 (PLA2), which have important antimicrobial activities. Bothrops erythromelas is one of the snake species in the northeast of Brazil that attracts great medical-scientific interest. Here, we aimed to purify and characterize a PLA2 from B. erythromelas, searching for heterologous activities against bacterial biofilms. Methods: Venom extraction and quantification were followed by reverse-phase high-performance liquid chromatography (RP-HPLC) in C18 column, matrix-assisted ionization time-of-flight (MALDI-ToF) mass spectrometry, and sequencing by Edman degradation. All experiments were monitored by specific activity using a 4-nitro-3-(octanoyloxy) benzoic acid (4N3OBA) substrate. In addition, hemolytic tests and antibacterial tests including action against Escherichia coli, Staphylococcus aureus, and Acinetobacter baumannii were carried out. Moreover, tests of antibiofilm action against A. baumannii were also performed. Results: PLA2, after one purification step, presented 31 N-terminal amino acid residues and a molecular weight of 13.6564 Da, with enzymatic activity confirmed in 0.06 µM concentration. Antibacterial activity against S. aureus (IC50 = 30.2 µM) and antibiofilm activity against A. baumannii (IC50 = 1.1 µM) were observed. Conclusions: This is the first time that PLA2 purified from B. erythromelas venom has appeared as an alternative candidate in studies of new antibacterial medicines.

Photoprotective Capabilities of Light-Harvesting Complex II Trimers in the Green Alga Chlamydomonas reinhardtii.

Major light-harvesting complex (LHCII) trimers in plants induce the thermal dissipation of absorbed excitation energy against photooxidative damage under excess light conditions. LHCII trimers in green algae have been thought to be incapable of energy dissipation without additional quencher proteins, although LHCIIs in plants and green algae are homologous. In this study, we investigated the energy-dissipative capabilities of four distinct types of LHCII trimers isolated from the model green alga Chlamydomonas reinhardtii using spectroscopic analysis. Our results revealed that the LHCII trimers possessing LHCII type II (LHCBM5) and LHCII type IV (LHCBM1) had efficient energy-dissipative capabilities, whereas LHCII type I (LHCBM3/4/6/8/9) and type III (LHCBM2/7) did not. On the basis of the amino acid sequences of LHCBM5 and LHCBM1 compared with the other LHCBMs, we propose that positively charged extra N-terminal amino acid residues mediate the interactions between LHCII trimers to form energy-dissipative states.

Formation, isomerization, and dissociation of tyrosine-containing tripeptide radical cations

Two series of tripeptide radical cations ([AYG] · +, [AYG · ]+; [GYG] · +, [G · YG]+ and [GYG · ]+) were successfully prepared via multistage collision-induced dissociation (CID) of a ternary complex of copper-ligand-tripeptide [Cu(L)Peptide]2+ (L=4′-chloro-2,2′:6′,2′′terpyridine (4Cl-tpy); Peptide=alanyl-tyrosyl-glycine (AYG) or glycyl-tyrosyl-glycine (GYG) tripeptide). The gas-phase isomerization and dissociation mechanism of isomeric AYG radical ions, and the different dissociation behaviors between AYG and GYG radical ions, have been obtained by observing their gas-phase dissociation reactions combined with density functional theory (DFT) calculation. Studies have revealed that: (1) [AYG · ]+ and [AYG] · + produced almost identical CID spectra (their main product ions are [x2+H] · + ions), suggesting that interconversion occurs prior to dissociation. (2) The dissociation paths of [A · YG]+ and [G · YG]+ are the same (both of which produces [b2−H] · + fragment ions by cleavage of amide C−N bond, indicating that [A · YG]+ cannot isomerize to [AYG · ]+ and [AYG] · +. DFT calculation gives the gas-phase stability order of these three peptide radical ions ([A · YG]+ > [AYG · ]+ > [AYG] · +) and their isomerization/dissociation energy barriers. Isomerization energy barrier (47.4 kcal/mol) of [AYG · ]+ ® [AYG] · + is lower than dissociation energy barrier (72.7 kcal/mol) of [AYG · ]+, but higher than that (44.3 kcal/mol) of [AYG] · +, thereby the gas-phase dissociation mechanism of [AYG · ]+ undergoes a two-step reaction: the first step is the isomerization process of [AYG · ]+ ® [AYG] · +, and the second step is the dissociation reaction of [AYG] · + ® [x2+H] · +, which produces [x2+H] · + fragment ions by cleavage of N-terminal Cα−C bond in [AYG] · +. (4) The gas-phase dissociation characteristics of [GYG] · + and [AYG] · + are dramatically different. [GYG] · + mainly produces [z2−H] · + by cleavage of the second N−Cα bond (counting from the N-terminal amino acid residue).

Guest-responsive supramolecular hydrogels expressing selective sol–gel transition for sulfated glycosaminoglycans

This paper describes the stimuli-responsive hydrogels constructed from bola-type amphiphiles composed of two dipeptides containing phenylalanine attached to the ends of a hydrophobic tetrathiophene. The hydrogel formation ability of the amphiphiles was affected by the N-terminal amino acid residue, which is an amphiphile-possessing phenylalanine-lysine sequence that formed a hydrogel under limited pH conditions. Gel formation occurred because of the phase transition of the gelator assembly from a granular aggregate to a fibrous architecture, in a process controlled by pH. This stimuli-responsive sol–gel transition was also accomplished by the addition of an anionic polymer, and sulfated glycosaminoglycans were successfully discriminated using the hydrogel system. A bola-type π-conjugated amphiphile containing Phe-Lys dipeptide showed a pH- and guest-induced phase transition from the granular aggregate to the fibrous architecture and formed a supramolecular hydrogel. Using this stimuli-responsiveness, the hydrogel system was successfully applied to the selective discrimination of glycosaminoglycans composed of a sulfated sugar unit.

Alternative Variants of Pax4 Human Transcription Factor: Comparative Transcriptional Activity

MODY is a group of genetically and clinically heterogeneous forms of diabetes characterized by auto-somal dominant inheritance and is subdivided in 13 subtypes dependent on the gene involved. The subtype MODY9 is a very rare form caused by mutations in the gene encoding the PAX4 transcription factor which is engaged in differentiation of pancreatic beta-cells. PAX4 contains two DNA-binding domains-Paired and Homeo. Expression of the human PAX4 gene is tissue-specific. The alternatively spliced mRNA variants encode for protein isoforms which differ within their N- and C-terminal regions. In this study, the transcriptional activities of the human PAX4 variants, both known and new ones, were determined. The full-length PAX4 containing intact DNA-binding domains was found to have maximal activity in transient expression system of the firefly luciferase reporter gene under control of the insulin promoter in HEK293 cells. The transcriptional activity is significantly reduced in the variants lacking eight N-terminal amino acid residues and/or variants whose Homeo domain is truncated from the C-terminus. Similar data were obtained with the glucagon promoter reporter system. The aberrant PAX4 variants were shown to retain stability and nuclear localization.

Removal of N-terminal tail changes the thermostability of the low-temperature-active exo-inulinase InuAGN25

ABSTRACT Exo-inulinases are members of the glycoside hydrolase family 32 and function by hydrolyzing inulin into fructose with yields up to 90–95%. The N-terminal tail contributes to enzyme thermotolerance, which plays an important role in enzyme applications. However, the role of N-terminal amino acid residues in the thermal performance and structural properties of exo-inulinases remains to be elucidated. In this study, three and six residues of the N-terminus starting from Gln23 of the exo-inulinase InuAGN25 were deleted and expressed in Escherichia coli. After digestion with human rhinovirus 3 C protease to remove the N-terminal amino acid fusion sequence that may affect the thermolability of enzymes, wild-type RfsMInuAGN25 and its mutants RfsMutNGln23Δ3 and RfsMutNGln23Δ6 were produced. Compared with RfsMInuAGN25, thermostability of RfsMutNGln23Δ3 was enhanced while that of RfsMutNGln23Δ6 was slightly reduced. Compared with the N-terminal structures of RfsMInuAGN25 and RfsMutNGln23Δ6, RfsMutNGln23Δ3 had a higher content of (1) the helix structure, (2) salt bridges (three of which were organized in a network), (3) cation–π interactions (one of which anchored the N-terminal tail). These structural properties may account for the improved thermostability of RfsMutNGln23Δ3. The study provides a better understanding of the N-terminus–function relationships that are useful for rational design of thermostability of exo-inulinases.

Enhanced CD8+ T-cell response in mice immunized with NS1-truncated influenza virus

Influenza viruses with truncated NS1 protein stimulate a more intensive innate immune response compared to their wild type counterparts. Here, we investigate how the shortening of the NS1 protein influence the immunogenicity of the conserved T-cellular epitopes of influenza virus. Using flow cytometry, we showed that the intraperitoneal immunization of mice with influenza virus encoding 124 N-terminal amino acid residues of the NS1 protein (A/PR8/NS124) induced higher levels of CD8+ T-cells recognizing immunodominant (NP366-374) and sub-immunodominant (NP161-175, NP196-210, HA323-337, HA474-483, NA427-433) epitopes compared to immunization with the virus expressing full-length NS1 (A/PR8/full NS). It is noteworthy that the response to the immunodominant influenza epitope NP366-374 was achieved with the lower immunization dose of A/PR8/NS124 virus compared to the reference wild type strain. Despite the fact that polyfunctional CD8+ effector memory T-lymphocytes simultaneously producing two (IFNγ and TNFα) or three (IFNγ, IL2, and TNFα) cytokines prevailed in the immune response to both viruses, the relative number of such T-cells was higher in A/PR8/NS124-immunized mice. Furthermore, we have found that polyfunctional populations of lymphocytes generated upon the immunization of mice with the mutant virus demonstrated an increased capacity to produce IFNγ compared to the corresponding populations derived from the A/PR8/full NS-immunized mice. Therefore, immunization with the attenuated influenza virus encoding truncated NS1 protein ensures a more potent CD8+ T-cell immune response.

THE CORTICOSTATIC EFFECT OF HUMAN LACTOFERRIN DEPENDS ON THE AMINO ACID COMPOSITION OF THE N-TERMINUS OF THE MOLECULE

The effect of various structural variants of human lactoferrin on stress-induced changes in the corticosterone level in the blood in rats was studied. A model of combined emotional and physical stress - swimming in cold water (1-4 °C) for 2 minutes. The level of corticosterone in plasma was determined by enzyme immunoassay. We have previously found that preventive intraperitoneal administration of native lactoferrin reduces the stress-induced increase in corticosterone concentration in the blood of rats 30 minutes after stress. This work shows that transgenic human lactoferrin, which lacks four arginine residues at the N-terminus, does not have this effect. The obtained results allow us to conclude about the key role of N-terminal amino acid residues in the implementation of the corticostatic activity of lactoferrin.

Anti-Microbial and Anti-Cancer Properties of Tat-IV13, A Hybrid Bi-Partite Peptide Containing The Short Non Active Iv13 Sequence of Human Ll37 Cathelecidin

Therapeutic strategies based on optimization of the unique human LL37 cathelecin sequences including FK16, the core active sequence of LL37, have already been proposed. In this study we have characterized TatIV13 a new host defense hybrid peptide, that combined YGRRKKRRQRRR, the hydrophobic N-terminal fragment of HIV-1 Tat47-57 cell penetrating sequence, with IV13, a short IVQRIKDFLRNLV inactive sequence resulting from the deletion of the three N-terminal amino acid residues of FK16. Tat- IV13 displayed potent host defense inhibitory effects leading both to the survival inhibition of U87G cells, a glioblastoma model, and to the inhibition of the growth of S. agalactiae NEM316 ΔdltA strain, a Gram+ bacterial model. These results suggest that identification of hybrid specific Tat-cathelecidin peptides with high anti-tumor activity and anti-bactericidal activity may represent a powerful approach to identify new candidates for future therapeutic developments.

Structure-activity relationship studies of shortened analogues of the antimicrobial peptide EeCentrocin 1 from the sea urchin Echinus esculentus.

EeCentrocin 1 is a potent antimicrobial peptide isolated from the marine sea urchin Echinus esculentus. The peptide has a hetero-dimeric structure with the antimicrobial activity confined in its largest monomer, the heavy chain (HC), encompassing 30 amino acid residues. The aim of the present study was to develop a shorter drug lead peptide using the heavy chain of EeCentrocin 1 as a starting scaffold and to perform a structure-activity relationship study with sequence modifications to optimize antimicrobial activity. The experiments consisted of 1) truncation of the heavy chain, 2) replacement of amino acids unfavourable for in vitro antimicrobial activity, and 3) an alanine scan experiment on the truncated and modified heavy chain sequence to identify essential residues for antimicrobial activity. The heavy chain of EeCentrocin 1 was truncated to less than half its initial size, retaining most of its original antimicrobial activity. The truncated and optimized lead peptide (P6) consisted of the 12 N-terminal amino acid residues from the original EeCentrocin 1 HC sequence and was modified by two amino acid replacements and a C-terminal amidation. Results from the alanine scan indicated that the generated lead peptide (P6) contained the optimal sequence for antibacterial activity, in which none of the alanine scan peptides could surpass its antimicrobial activity. The lead peptide (P6) was also superior in antifungal activity compared to the other peptides prepared and showed minimal inhibitory concentrations (MICs) in the low micromolar range. In addition, the lead peptide (P6) displayed minor haemolytic and no cytotoxic activity, making it a promising lead for further antimicrobial drug development.

Diverse roles of arrest defective 1 in cancer development.

Arrest defective 1 is an acetyltransferase that acetylates N-terminal amino acid or internal lysine residues of its target proteins. By acetylating its target proteins, ARD1 plays roles in many cellular activities, including proliferation, differentiation, autophagy, and apoptosis. In recent years, a number of investigations have emerged reporting the dysregulated expression of ARD1 in different types of cancer, including lung, liver, pancreas, breast, prostate, and colon cancer. Furthermore, the expression level of ARD1 in cancer tissues has been correlated with the progression and metastasis of the cancer and the survival of cancer patients. Consequently, mechanistic studies have revealed that ARD1-mediated protein acetylation plays an important role in modulating several cellular events that are important for cancer development, such as cell cycle progression, cell death, and migration. On the basis of this evidence, targeting of ARD1 has been proposed as a promising avenue for the development of novel cancer therapeutics. This review summarizes the biological functions of ARD1 in different types of cancer and provides a deep insight into the biochemical activities of ARD1 during tumor progression.

MeCP2-E1 isoform is a dynamically expressed, weakly DNA-bound protein with different protein and DNA interactions compared to MeCP2-E2

BackgroundMeCP2—a chromatin-binding protein associated with Rett syndrome—has two main isoforms, MeCP2-E1 and MeCP2-E2, differing in a few N-terminal amino acid residues. Previous studies have shown brain region-specific expression of these isoforms which, in addition to their different cellular localization and differential expression during brain development, suggest that they may also have non-overlapping molecular mechanisms. However, differential functions of MeCP2-E1 and E2 remain largely unexplored.ResultsHere, we show that the N-terminal domains (NTD) of MeCP2-E1 and E2 modulate the ability of the methyl-binding domain (MBD) to interact with DNA as well as influencing the turn-over rates, binding dynamics, response to neuronal depolarization, and circadian oscillations of the two isoforms. Our proteomics data indicate that both isoforms exhibit unique interacting protein partners. Moreover, genome-wide analysis using ChIP-seq provide evidence for a shared as well as a specific regulation of different sets of genes.ConclusionsOur study supports the idea that Rett syndrome might arise from simultaneous impairment of cellular processes involving non-overlapping functions of MECP2 isoforms. For instance, MeCP2-E1 mutations might impact stimuli-dependent chromatin regulation, while MeCP2-E2 mutations could result in aberrant ribosomal expression. Overall, our findings provide insight into the functional complexity of MeCP2 by dissecting differential aspects of its two isoforms.

Characterization of a novel multi-domain xylanase from Clostridium clariflavum with application in hydrolysis of corn cobs

To develop a novel multi-catalytic domain (CD) xylanase Xyn2083 from Clostridium clariflavum by expression of its truncated forms in Escherichia coli and cooperation of xylanase with cellulase in the hydrolysis of waste lignocellulosic resources. Xyn2083 has two glycoside hydrolase family (GH) domains GH11 and GH10. These two catalytic domains functioned synergistically in xylan hydrolysis. The recombinant protein with GH11 domain, Xyn2083GH11, had the highest xylanase activity among three constructed truncated forms. The deletion of N-terminal extra amino acid residues of Xyn2083GH11 decreased catalytic activity as well as the stability of the enzyme. The hydrolysis rates of cellulose and xylan in the pretreated corn cobs were 90.56% and 72.80% with the addition of Xyn2083GH11 and cellulase, whereas those were 67.95% and 34.45% using sole cellulase respectively. The structural analysis of substrates indicated that the addition of Xyn2083GH11 led to a looser structure and more exposure of crystal cellulose for cellulase to approach. Since the native multi-CDs' xylanases are rare, the thermostable Xyn2083 provides a good source for functional studies of two CDs coexisted in one xylanase and for potential applications after modification.

Comprehensive analysis of a dipeptide library to identify ghrelin release-modulating peptides.

We performed a comprehensive analysis of ghrelin release-modulating activity of a dipeptide library using MGN3-1, a ghrelin-producing cell line. We found that most dipeptides suppress ghrelin secretion, whereas the N-terminal Ser-containing dipeptides and a few others stimulate it. N-terminal amino acid residues, but not C-terminal residues, play a dominant role in the effects of dipeptides. Among dipeptides, Leu-Ile (LI) and Ser-Val (SV) most strongly suppress and stimulate ghrelin secretion, respectively. LI activates Gi signaling and SV acts via the MAPK pathway. Orally administered LI and SV reduce and increase plasma ghrelin levels and food intake in mice, respectively. In conclusion, LI and SV, found based on the comprehensive screening of a dipeptide library, modulate ghrelin secretion invitro and invivo.

Expression in Lactococcus lactis of a β-1,3-1,4-glucanase gene from Bacillus sp. SJ-10 isolated from fermented fish

Bacterial β-1,3-1,4-glucanase (BG) is an endoglucanase that hydrolyzes linear β-glucans containing β-1,3 and β-1,4 linkages, such as barley β-glucans. In this study, a BG gene was transformed into the food-grade plasmid pNZ8149 and successfully expressed in Lactococcus lactis NZ3900 using the nisin-controlled gene expression system. To facilitate extracellular secretion, the signal peptide Usp45 was added during vector construction. A histidine tag was also added for affinity purification. BG was extracellularly secreted and was also present in the cells in soluble form. N-terminal amino acid residue analysis of secreted BG revealed that the Usp45 peptide was removed. The optimum temperature and pH for both intracellular and extracellular BG were 40 °C and 6, respectively. The enzyme kinetic parameters, Vmax, Km, kcat, and kcat/Km, of extracellular BG were 1317.51 μmol min−1, 1.97 mg ml−1, 588.54 s−1, and 298.26 ml s−1∙mg−1, respectively. There was no significant difference in the enzyme kinetic parameters of intracellular and extracellular BG. The growth pattern of transformed L. lactis NZ3900 in β-glucan-containing liquid medium confirmed β-glucan degradation by BG. The transformed strain degraded β-glucans, produced gluco-oligosaccharide, and produced lactic acid. The strain and expression system constructed in this study could be applied to industrial fields requiring BG produced in food-grade lactococcal secretory expression system.

The identification and chromatographic separation of a new highly analogous impurity of the active pharmaceutical ingredient icatibant

Icatibant is a peptidomimetic drug serving as a bradykinin-receptor antagonist and is approved in Europe and the United States for the treatment of hereditary angioedema attacks. We have detected an impurity with a high structural similarity to icatibant in pharmaceutical dosage forms using an optimized chromatographic method based on reversed phase high performance liquid chromatography with UV detection. The abundance of the impurity was around 1% relative to the icatibant peak following storage at room temperature for 1 month, and raised up to ~16% upon temperature stressing at 100 °C. The impurity was isolated by fraction collection and further purified by solid phase extraction for structural identification. NMR and high resolution mass spectrometric analyses revealed that this impurity results from isomerization in the N-terminal single amino acid residue. The new impurity may warrant particular attention due to its exceptional similarity to the active ingredient icatibant.

Purification and characterization of lysozyme from Chinese Lueyang black-bone Silky fowl egg white

Lysozyme, an important antibacterial protein, is an enzyme that cleaves the glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine of peptidoglycan in cell walls. The novel lysozyme was purified and characterized from Chinese Lueyang black-bone silky fowl (CBSF) egg white, and its N-terminal amino acid sequence, enzymatic properties, and antibacterial activity were investigated. The CBSF lysozyme was purified using adsorption chromatography, ammonium sulfate precipitation, ion exchange chromatography, and size-exclusion chromatography. The purification fold and yield were 3.28 and 14.69%, respectively. The purified lysozyme was revealed as a single protein band with SDS–PAGE and had a MALDI-TOF/TOF molecular weight of 14305.57 Da and a final specific activity of 3.49 × 105 U/mg protein using Micrococcus lysodeikticus as a substrate. The optimum temperature and pH of the lysozyme were 50 °C and 6.0, respectively. The 20 N-terminal amino acid residues of the purified lysozyme were determined to be KVFGRCELAAAMKRHGLDNY, showing some homology to the N-terminus of the odontophoridae egg white lysozyme. The purified lysozyme exerted a potent antimicrobial activity toward indicator microorganisms, including Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 25923, and Escherichia coli ATCC 25922. However, its inhibition of gram-negative activity was weaker than that of the Gram-positive bacteria.

Design, Synthesis and Interaction of BRCA1 Peptide Fragments with RAD51(181–200)

Six breast cancer susceptibility gene 1 (BRCA1) peptide fragments were designed by removing N-terminal amino acid residues of BRCA1(846–871). Peptide fragments BRCA1(846–871), BRCA1(852–871), BRCA1(854–871), BRCA1(856–871), BRCA1(857–871) and BRCA1(861–871) were obtained by Fmoc solid-phase synthesis, purified by reversed-phase high-performance liquid chromatography and characterized by electrospray ionization mass spectrometry. The interaction between BRCA1 fragment peptides and RAD51(181–200) target peptides were investigated using circular dichroism (CD) spectroscopy, fluorescence spectroscopy, and microscale thermophoresis (MST). The results of CD spectroscopy showed that the secondary structures of RAD51(181–200) were altered after the addition of BRCA1 peptide fragments. The fluorescence results proved that all six BRCA1 peptide fragments BRCA1(846–871), BRCA1(852–871), BRCA1(854–871), BRCA1(856–871), BRCA1(857–871) and BRCA1(861–871) could bind to RAD51(181–200) independently, their quenching processes were static, and the binding constant of peptide fragments with RAD51(181–200) were 4.01 × 105 L mol−1, 7.22 × 105 L mol−1, 7.84 × 105 L mol−1, 1.1 × 104 L mol−1, 6.19 × 103 L mol−1, 6.18 × 103 L mol−1. The results of MST displayed that BRCA1(854–871) could combine with RAD51(181–200), and the dissociation constant Kd was 126.44 µM. Compared with other five peptide fragments, the interaction between BRCA1(854–871) and RAD51(181–200) was much stronger.

Direct interaction between the PRDM3 and PRDM16 tumor suppressors and the NuRD chromatin remodeling complex.

Aberrant isoform expression of chromatin-associated proteins can induce epigenetic programs related to disease. The MDS1 and EVI1 complex locus (MECOM) encodes PRDM3, a protein with an N-terminal PR-SET domain, as well as a shorter isoform, EVI1, lacking the N-terminus containing the PR-SET domain (ΔPR). Imbalanced expression of MECOM isoforms is observed in multiple malignancies, implicating EVI1 as an oncogene, while PRDM3 has been suggested to function as a tumor suppressor through an unknown mechanism. To elucidate functional characteristics of these N-terminal residues, we compared the protein interactomes of the full-length and ΔPR isoforms of PRDM3 and its closely related paralog, PRDM16. Unlike the ΔPR isoforms, both full-length isoforms exhibited a significantly enriched association with components of the NuRD chromatin remodeling complex, especially RBBP4. Typically, RBBP4 facilitates chromatin association of the NuRD complex by binding to histone H3 tails. We show that RBBP4 binds to the N-terminal amino acid residues of PRDM3 and PRDM16, with a dissociation constant of 3.0 μM, as measured by isothermal titration calorimetry. Furthermore, high-resolution X-ray crystal structures of PRDM3 and PRDM16 N-terminal peptides in complex with RBBP4 revealed binding to RBBP4 within the conserved histone H3-binding groove. These data support a mechanism of isoform-specific interaction of PRDM3 and PRDM16 with the NuRD chromatin remodeling complex.