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Phosphate acquisition components of the Myxococcus xanthus Pho regulon are regulated by both phosphate availability and development.

Abstract：

:In many organisms, phosphatase expression and phosphate (P) uptake are coordinately regulated by the Pho regulon. In Myxococcus xanthus P limitation initiates multicellular development, a process associated with changes in phosphatase expression. We sought here to characterize the link between P acquisition and development in this bacterium, an organism capable of preying upon other microorganisms as a sole nutrient source. M. xanthus seems to possess no significant internal P stores, as reducing the P concentration to less than 10 microM retarded growth within one doubling time. Pyrophosphate, polyphosphate, and glyceraldehyde-3-phosphate could support growth as sole P sources, although many other P-containing biomolecules could not (including nucleic acids and phospholipids). Several Pho regulon promoters were found to be highly active during vegetative growth, and P limitation specifically induced pstSCAB, AcPA1, and pho3 promoter activity and repressed pit expression. Enhanced pstSCAB and pho3 promoter activities in a phoP4 mutant (in the presence of high and low concentrations of P) suggested that PhoP4 acts as a repressor of these genes. However, in a phoP4 background, the activities of pstSCAB remained P regulated, suggesting that there is additional regulation by a P-sensitive factor. Initiation of multicellular development caused immediate down-regulation of Pho regulon genes and caused pstSCAB and pho3 promoter activities to become P insensitive. Hence, P acquisition components of the M. xanthus Pho regulon are regulated by both P availability and development, with developmental down-regulation overriding up-regulation by P limitation. These observations suggest that when development is initiated, subsequent changes in P availability become irrelevant to the population, which presumably has sufficient intrinsic P to ensure completion of the developmental program.

journal_name

J Bacteriol

journal_title

Journal of bacteriology

authors

Whitworth DE,Holmes AB,Irvine AG,Hodgson DA,Scanlan DJ

doi

10.1128/JB.01781-07

subject

Has Abstract

pub_date

2008-03-01 00:00:00

pages

1997-2003

issue

eissn

0021-9193

issn

1098-5530

pii

JB.01781-07

journal_volume

190

pub_type

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Phosphate acquisition components of the Myxococcus xanthus Pho regulon are regulated by both phosphate availability and development.