Common Biosynthetic Pathway Research Articles

Sequence homology between the tyrosine-sensitive 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase from Escherichia coli and hemerythrin from Sipunculida.

The first enzyme of the common aromatic biosynthetic pathway in Escherichia coli, the 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase, contains iron as an integral part of the polypeptide chain, and the enzyme shows an absorption maximum around 350 nm (McCandliss, R.J., and Herrmann, K.M. (1978) Proc. Natl. Acad. Sci. U. S. A. 75, 4810-4813). These two properties are also found in hemerythrin, the oxygen carrier of certain marine invertebrates. The amino acid sequence of residues 10 to 18 of the enzyme from E. coli, His-Ile-Thr-Asp-Glu-Gln-Val-Leu-Met, is highly homologous to the sequence of residues 54 to 62 of hemerythrin from Phascolopsis gouldii, His-Phe-Leu-Asn-Glu-Gln-Val-Leu-Met. His54 and Glu58 of hemerythrin have previously been identified through x-ray and protein sequence analysis as iron ligands. We suggest that residues 10 to 18 of the E. coli enzyme represent part of the iron binding fold in this protein, and that His10 and Glu14 are iron ligands.

Immunological studies on 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase isoenzymes.

An apparently homogeneous preparation of the phenylalanine-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase isoenzyme from Escherichia coli was used as the antigen for antibody production in New Zealand white rabbits. The antibodies were monospecific as judged by immunodiffusion and immunoelectrophoresis. Antigen . antibody complexes maintained full enzyme activity and were inhibited by phenylalanine, indicating that neither the active site nor the feedback-inhibitor binding site is mechanistically connected to amino acid sequences which are antigenic determinants. While phenylalanine-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase could be quantitatively removed from solution by immunoprecipitation with soluble or immobilized antibodies, neither the tyrosine-sensitive nor the tryptophan-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase, the other two isoenzymes catalyzing the first step in the biosynthesis of aromatic compounds, formed any detectable complexes with the antibodies. This indicated less structural similarity than would be expected for isoenzymes. Also, the antibodies did not cross-react with 5-dehydroquinate synthase, the enzyme catalyzing the second step of the common aromatic biosynthetic pathway.

Geographic patterns of monoterpenoid composition in Satureja douglasii

Monoterpenoid composition of mature leaves from populations distributed throughout the range of Satureja douglasii was determined by GLC. Five compositional types (I–V) were characterised, based on the high relative proportions of either carvone, pulegone, isomenthone, menthone or bicyclic compounds (camphenecamphor). These compositional types occured in restricted but overlapping portions of the species range. All samples contained camphene and camphor, amounts of which varied clinally along latitudinal gradient. Transplants were grown under greenhouse conditions. Although some populations exhibited significant environmental modification in amounts of principal constituents, the patterns of geographic variation were retained. Compositional types I–IV are based on compounds having ϱ-menthane structures and relationships among them are consistent with single gene actions within a common biosynthetic pathway. Using the dominant components of the collection site vegetation as an indication of habitat conditions, correlation of the genetically-determined compositional variation with environmental conditions was attempted. The distribution of the compositional types was partially isolated in this manner. Environmental factors which might be controlling the genetically-determined variation are discussed.

Separability of enzymes of the common aromatic biosynthetic pathway in Mycobacterium phlei

Separability of enzymes of the common aromatic biosynthetic pathway in Mycobacterium phlei

Structure and function of peptidoglycans

Detailed knowledge of bacterial cell wall peptidoglycan structures has expanded rapidly in the past few years, and very definite patterns have emerged which can be attributed to common biosynthetic pathways, and, more speculatively, to a common structural function. The glycan is β - 1, 4 linked and is therefore a substituted form of chitin, probably retaining its linear conformation. The peptide may be more flexible, and varied in its cross-linking, but all contain a sequence derived from a probable common precursor, UDP- N- acetylmuramy 1-(A)- D - glu -(B)- D -ala- D - ala, when (A) and (B) are amino acids with the carboxy 1 and α-amino groups of a center with L - configuration in the main chain. The conformation of this sequence is discussed.

The biosynthesis of phosphatides in several tissue-culture cell lines

HeLa (S3 clone) cells, bovine lymphosarcoma cells, monkey heart cells, and chick embryo endothelium cells were grown on Hanks' balanced Salt Solution supplemented with lactalbumin hydrolysate and bovine serum plus H32PO4 =. The various cell lines were labeled with inorganic 32P for varying periods of time. The phosphatides were extracted and deacylated with 0.1 N methanolic KOH at 37°C for 15 min. The deacylated phosphatides were separated by two-dimensional paper chromatography. The total phosphatide relative activity (cpm/wt protein/μg 32P applied) was determined at various times. The percent of the total phosphatide activity with time for each phosphatide was also determined. The phosphatide relative activity-time relationships demonstrated that each of the four cell lines studied varied in their phosphatide relative activities. This determination allows identification of these cell lines grown in culture. The ratio of relative activities of 32P-phosphatides to 32P-organic compounds indicated that phosphorus was utilized in the HeLa cell line preferentially for the synthesis of phosphorus compounds other than phosphatides. These other phosphorus compounds may be nucleic acids. Determinations of the per cent of total phosphatide activity for individual phosphatides in three cell lines presented evidence of a common biosynthetic pathway for phosphatides. Biosynthetic interrelationships of phosphatides were postulated to satisfy the sequential labeling of those phosphatides in both plants and animals. It was impossible to distinguish any basic difference between malignant and normal cells in culture by the procedures employed herein.