Previous Article | Next Article ![]()
Appl. Environ. Microbiol., Mar 1995, 972-978, Vol 61, No. 3
S Babu-Khan, TC Yeo, WL Martin, MR Duron, RD Rogers and AH Goldstein
We have recently shown that the ability of some gram-negative bacteria to
dissolve poorly soluble calcium phosphates (Mps+ phenotype) is the result
of periplasmic oxidation of glucose to gluconic acid via the quinoprotein
glucose dehydrogenase (GDH), a component of the direct oxidation pathway.
Escherichia coli K-12 derivatives synthesize apo-GDH but not the cofactor
pyrroloquinoline-quinone (PQQ) essential for formation of the holoenzyme.
Therefore, in the absence of exogenous PQQ, these strains do not produce
gluconic acid and are Mps-. Evidence is presented to show that expression
of a single 396-base Pseudomonas cepacia open reading frame (designated
gabY) in E. coli JM109 (a K-12 derivative) was sufficient to induce the
Mps+ phenotype and production of gluconic acid. We present the nucleotide
sequence of this open reading frame which coded for a protein (GabY) with a
deduced M(r) of 14,235. Coupled transcription-translation of a plasmid
(pSLY4 or pGAB1) carrying gabY resulted in production of a protein with an
M(r) of 14,750. Disruption of the open reading frame of gabY via
site-directed mutagenesis changed the phenotype to Mps- and eliminated
gluconic acid production. The deduced amino acid sequence of gabY has no
apparent homology with those of previously cloned direct oxidation pathway
genes but does share regions highly homologous with the histidine permease
system membrane-bound protein HisQ as well as other proteins in this
family. In the presence of 1 microM exogenous PQQ, both JM109(pSLY4) and
JM109(pGAB1) produced 10 times as much gluconic acid as was seen with
either the plasmid or exogenous PQQ alone.(ABSTRACT TRUNCATED AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
Cloning of a mineral phosphate-solubilizing gene from Pseudomonas cepacia
Department of Biology, California State University at Los Angeles 90032.
This article has been cited by other articles:
| J. Bacteriol. | Microbiol. Mol. Biol. Rev. | Eukaryot. Cell | All ASM Journals |
|---|