Beta-Hydroxylation of the aspartyl residue in the phytotoxin syringomycin E: characterization of two candidate hydroxylases AspH and SyrP in Pseudomonas syringae.

ABSTRACT: The pseudomonal phytotoxin syringomycin E and related nonribosomal peptides contain an L- threo-beta-hydroxyaspartyl residue at the eighth position of the lipodepsipeptide backbone as part of a conserved nonproteinogenic tripeptide motif. Informatic analysis of the P. syringae genome suggests only one putative non-heme iron hydroxylase, AspH. On heterologous expression in Escherichia coli AspH shows robust catalytic activity with free L-Asp and L-Asp thioesters to make beta-OH-Asp but yields the erythro diastereomer rather than the threo configuration that is found in syringomycin. Further analysis of the Syr gene cluster indicated that SyrP, previously annotated as the gene regulatory protein for the five-gene Syr cluster, is actually homologous to the known non-heme mononuclear iron hydr

SUBMITTER: Singh GM 

PROVIDER: S-EPMC2600472 | biostudies-literature | 2008 Oct

REPOSITORIES: biostudies-literature