A possible role for acetylated intermediates in diaminopimelate and tabtoxinine-beta-lactam biosynthesis in Pseudomonas syringae pv. tabaci BR2.024

• Published in: Journal of Bacteriology Vol. 179; no. 18; pp. 5922 - 5927
• Main Authors: Liu, L, Shaw, P.D
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01-09-1997
• Subjects: Acetylation; Acetyltransferases - genetics; Acetyltransferases - metabolism; ACIDE AMINE; ACILTRANSFERASA; ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; ACYLTRANSFERASE; ACYLTRANSFERASES; Acyltransferases - genetics; Amino Acid Sequence; AMINO ACID SEQUENCES; AMINO ACIDS; AMINOACIDOS; Azetidines - metabolism; Bacterial Proteins; BACTERIAL TOXINS; Bacteriology; Base Sequence; beta-Lactams - metabolism; BIOSINTESIS; BIOSYNTHESE; BIOSYNTHESIS; CHEMICAL COMPOSITION; Cloning, Molecular; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; DIAMINOPIMELIC ACID; Diaminopimelic Acid - metabolism; ENZYMIC ACTIVITY; Escherichia coli - genetics; GENBANK/M88485; GENE; GENES; Genes, Bacterial; Genetic Complementation Test; Lysine - biosynthesis; MESO-DAP DEHYDROGENASE; MOLECULAR SEQUENCE DATA; NUCLEOTIDE SEQUENCE; OPEN READING FRAMES; OXIDOREDUCTASES; OXIDORREDUCTASAS; OXYDOREDUCTASE; PROMOTERS; Pseudomonas - metabolism; PSEUDOMONAS SYRINGAE; Restriction Mapping; SECUENCIA NUCLEOTIDICA; Sequence Alignment; Sequence Homology, Amino Acid; SEQUENCE NUCLEOTIDIQUE; STRUCTURAL GENES; TABB GENE; TOXINAS BACTERIANAS; TOXINE BACTERIENNE
• ISSN: 0021-9193; 1098-5530; 1067-8832
• DOI: 10.1128/jb.179.18.5922-5927.1997

The deduced product of an open reading frame (ORF3) located in the tabtoxinine-beta-lactam (TbetaL) biosynthetic region of Pseudomonas syringae pv. tabaci BR2.024 (BR2.024) has significant sequence homology to the dapD products of other bacteria. dapD encodes L-2,3,4,5-tetrahydrodipicolinate succinyl coenzyme A succinyl-transferase (THDPA-ST), an enzyme in the diaminopimelate (DAP) and lysine biosynthetic pathway. Complementation studies, in vitro transcription-translation experiments, and enzymatic assays indicated that ORF3 encodes a product with THDPA-ST activity in Escherichia coli dapD mutant beta 274. However, a BR2.024 mutant with an insert in ORF3 was prototrophic, and only basal THDPA-ST activity was detected in extracts of both parent and mutant. This finding suggested that ORF3 was not required for DAP biosynthesis and that it did not encode a product with THDPA-ST activity. The results of enzymatic studies indicating that BR2.024 uses acetylated intermediates for DAP biosynthesis, are consistent with the hypothesis that BR2.024 does not need THDPA-ST for DAP biosynthesis. The ORF3 mutant produced reduced levels of tabtoxin, indicating that ORF3 may have a role in TbetaL biosynthesis. We have named the gene tabB and have proposed a possible function for the gene product