Premium
Proteomic analysis of the Caulobacter crescentus stalk indicates competence for nutrient uptake
Author(s) -
Ireland Marcia M. E.,
Karty Jonathan A.,
Quardokus Ellen M.,
Reilly James P.,
Brun Yves V.
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.03071.x
Subject(s) - caulobacter crescentus , stalk , biology , flagellum , microbiology and biotechnology , proteome , cell division , biochemistry , response regulator , peptidoglycan , cell wall , mutant , cell , gene , bacterial protein , horticulture
Summary Caulobacter crescentus, a Gram‐negativeα‐purple proteobacterium, is an oligotroph that lives in aquatic environments dilute in nutrients. This bacterium divides asymmetrically. Part of this asymmetric cell division involves the formation of a prosthecum at one pole, referred to as the stalk, which replaces the flagellum of the motile swarmer cell. Little is known about the synthesis or function of the stalk. The stalk is an extension of the cell membranes and peptidoglycan layer, and stalk elongation is stimulated by phosphate starvation. In this study, we have taken advantage of two‐dimensional gel (2D gel) electro‐phoresis as well as the fully sequenced genome ofCaulobacterto study the proteome of the stalk. We modified a stalk‐shedding mutant strain ofCaulobacter crescentusto increase the yield of stalk material shed and performed 2D gel electrophoresis of purified stalks and cellular fractions. Comparison of the stalk 2D gel with the 2D gels of cell membrane and soluble fractions showed that the stalk is mostly free of cytoplasmic proteins and has a profile very similar to that of the cell membrane. Of the 172 proteins on a stalk 2D gel, we report the identification of 64 spots, corresponding to 39 different proteins present in the stalk ofCaulobacter. The identifications include several TonB‐dependent receptors, two OmpA family proteins, a dipeptidase, GlpQ, two alkaline phosphatases, 3‐phytase, a putative TolC protein and 11 proteins of unknown function. These identifications are consistent with the hypothesis that the stalk plays a role in nutrient uptake.