Identification and Localization of Myxococcus xanthus Porins and Lipoproteins

Bhat, Swapna; Zhu, Xiang; Patel, Ricky P.; Orlando, Ron; Shimkets, Lawrence J.

doi:10.1371/journal.pone.0027475

Cited by 25 publications

(29 citation statements)

References 58 publications

(70 reference statements)

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“…Membrane fractionation indicated that CsgA is an inner membrane protein (Simunovic et al 2003), not an outer membrane protein as previously reported (Lobedanz and Sogaard-Andersen 2003). Extensive proteomic studies have likewise never placed CsgA in the outer membrane or on the cell surface (Kahnt et al 2010;Bhat et al 2011), and no receptor has ever been identified. The p17 form lacks the N-terminal NAD + -binding domain, and genomic replacement of a truncated csgA gene encoding an 18.1-kDa protein abolishes development (Lobedanz and Sogaard-Andersen 2003).…”

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confidence: 59%

Myxococcus CsgA, Drosophila Sniffer, and human HSD10 are cardiolipin phospholipases

Boynton

Shimkets

2015

Genes Dev.

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Myxococcus xanthus development requires CsgA, a member of the short-chain alcohol dehydrogenase (SCAD) family of proteins. We show that CsgA and SocA, a protein that can replace CsgA function in vivo, oxidize the 2 ′ -OH glycerol moiety on cardiolipin and phosphatidylglycerol to produce diacylglycerol (DAG), dihydroxyacetone, and orthophosphate. A lipid extract enriched in DAGs from wild-type cells initiates development and lipid body production in a csgA mutant to bypass the mutational block. This novel phospholipase C-like reaction is widespread. SCADs that prevent neurodegenerative disorders, such as Drosophila Sniffer and human HSD10, oxidize cardiolipin with similar kinetic parameters. HSD10 exhibits a strong preference for cardiolipin with oxidized fatty acids. This activity is inhibited in the presence of the amyloid β peptide. Three HSD10 variants associated with neurodegenerative disorders are inactive with cardiolipin. We suggest that HSD10 protects humans from reactive oxygen species by removing damaged cardiolipin before it induces apoptosis.

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confidence: 59%

Myxococcus CsgA, Drosophila Sniffer, and human HSD10 are cardiolipin phospholipases

Boynton

Shimkets

2015

Genes Dev.

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“…5A), suggesting that this domain plays a critical A motility function. Prior proteomic studies found the CglD lipoprotein (MXAN_0962) in the inner membrane or OM and OM vesicles (OMVs) (2,13). These different findings may result from complex cell fractionation properties for a large protein that likely binds multiple factors.…”

Section: Discussionmentioning

confidence: 99%

Identification of the cglC , cglD , cglE , and cglF Genes and Their Role in Cell Contact-Dependent Gliding Motility in Myxococcus xanthus

Pathak

Wall

2012

J Bacteriol

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Within Myxococcus xanthus biofilms, cells actively move and exchange their outer membrane (OM) lipoproteins and lipids. Between genetically distinct strains, OM exchange can regulate recipient cell behaviors, including gliding motility and development. Although many different proteins are thought to be exchanged, to date, only two endogenous OM lipoproteins, CglB and Tgl, are known to be transferred. Protein exchange requires the TraAB proteins in recipient and donor cells, where they are hypothesized to facilitate OM fusion for transfer. To better understand the types of proteins exchanged, we identified the genes for the remaining set of cgl gliding motility mutants. These mutants are unique because their motility defect can be transiently restored by physical contact with donor cells that encode the corresponding wild-type protein, a process called stimulation. Similar to CglB and Tgl, the cglC and cglD genes encode type II signal sequences, suggesting that they are also lipoproteins. Surprisingly, the cglE and cglF genes instead encode type I signal sequences, suggesting that nonlipoproteins are also exchanged. Consistent with this idea, the addition of exogenous synthetic CglF protein (71 amino acids) to a cglF mutant rescued its motility defect. In contrast to a live donor cell, stimulation with purified CglF protein occurred independently of TraA. These results also indicate that CglF may localize to the cell surface. The implications of our findings on OM exchange are discussed.

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“…If CsgA is an enzyme, its substrate and product remain to be identified. Interestingly, the outer membrane porin Oar is required for C signaling and has been proposed to be the channel for the export of the C signal (31). Cellular responses to C signaling involve FruA, which is similar to the response regulators of two-component signal transduction systems (32,33).…”

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confidence: 99%

Combinatorial Regulation of thedevOperon by MrpC2 and FruA during Myxococcus xanthus Development

et al. 2014

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Proper expression of the dev operon is important for normal development of Myxococcus xanthus. When starved, these bacteria coordinate their gliding movements to build mounds that become fruiting bodies as some cells differentiate into spores. Mutations in the devTRS genes impair sporulation. Expression of the operon occurs within nascent fruiting bodies and depends in part on C signaling. Here, we report that expression of the dev operon, like that of several other C-signal-dependent genes, is subject to combinatorial control by the transcription factors MrpC2 and FruA. A DNA fragment upstream of the dev promoter was bound by a protein in an extract containing MrpC2, protecting the region spanning positions ؊77 to ؊54. Mutations in this region impaired binding of purified MrpC2 and abolished developmental expression of reporter fusions. The association of MrpC2 and/or its longer form, MrpC, with the dev promoter region depended on FruA in vivo, based on chromatin immunoprecipitation analysis, and purified FruA appeared to bind cooperatively with MrpC2 to DNA just upstream of the dev promoter in vitro. We conclude that cooperative binding of the two proteins to this promoter-proximal site is crucial for dev expression. 5= deletion analysis implied a second upstream positive regulatory site, which corresponded to a site of weak cooperative binding of MrpC2 and FruA and boosted dev expression 24 h into development. This site is unique among the C-signal-dependent genes studied so far. Deletion of this site in the M. xanthus chromosome did not impair sporulation under laboratory conditions. Myxococcus xanthus is a Gram-negative bacterium that undergoes multicellular development (1). Upon starvation on a solid surface, cells coordinate their movements to build mounds that contain thousands of cells. Within these nascent fruiting bodies, some cells differentiate from rods to ovoid spores. Other cells lyse during the developmental process or remain outside fruiting bodies as peripheral rods. The spores remain viable during prolonged starvation and resist environmental insults. Under favorable conditions, spores germinate, producing rod-shaped cells capable of growth and division.The developmental process of M. xanthus provides an attractive model to study signaling and gene regulatory mechanisms (1). Here, we focus on regulation of the dev operon in response to extracellular C signaling. The dev locus was identified by two transposon insertions that created reporter fusions induced during development (2, 3). Expression from the fusions was reduced in a csgA mutant incapable of C signaling (4). The transposon insertions in the dev locus prevented darkening of nascent fruiting bodies and reduced sporulation Ͼ100-fold (3, 5). The sporulation defect can be accounted for by the observation that a dev mutant fails to express the ⍀7536 locus (6), the site of the exo operon, whose products are necessary for spore formation (7). How the products of the dev operon regulate the expression of the exo operon is unknown. The dev op...

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Identification and Localization of Myxococcus xanthus Porins and Lipoproteins

Cited by 25 publications

References 58 publications

Myxococcus CsgA, Drosophila Sniffer, and human HSD10 are cardiolipin phospholipases

Myxococcus CsgA, Drosophila Sniffer, and human HSD10 are cardiolipin phospholipases

Identification of the cglC , cglD , cglE , and cglF Genes and Their Role in Cell Contact-Dependent Gliding Motility in Myxococcus xanthus

Combinatorial Regulation of thedevOperon by MrpC2 and FruA during Myxococcus xanthus Development

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