Mutations in
            <i>Flavobacterium johnsoniae secDF</i>
            Result in Defects in Gliding Motility and Chitin Utilization

Nelson, Shawn S.; McBride, Mark J.

doi:10.1128/jb.188.1.348-351.2006

Cited by 15 publications

(10 citation statements)

References 29 publications

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“…ChiA has a predicted cleavable N-terminal signal peptide that is thought to target it to the Sec system for transit across the cytoplasmic membrane. Mutations in secDF result in decreased digestion of chitin (42), which is consistent with the involvement of the Sec system in export of ChiA. T9SS mediated secretion across the outer membrane may involve cleavage of the CTD from ChiA.…”

Section: Discussionsupporting

confidence: 57%

Flavobacterium johnsoniae Chitinase ChiA Is Required for Chitin Utilization and Is Secreted by the Type IX Secretion System

Kharade

McBride

2013

Journal of Bacteriology

110

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Flavobacterium johnsoniae, a member of phylum Bacteriodetes, is a gliding bacterium that digests insoluble chitin and many other polysaccharides. A novel protein secretion system, the type IX secretion system (T9SS), is required for gliding motility and for chitin utilization. Five potential chitinases were identified by genome analysis. Fjoh_4555 (ChiA), a 168.9-kDa protein with two glycoside hydrolase family 18 (GH18) domains, was targeted for analysis. Disruption of chiA by insertional mutagenesis resulted in cells that failed to digest chitin, and complementation with wild-type chiA on a plasmid restored chitin utilization. Antiserum raised against recombinant ChiA was used to detect the protein and to characterize its secretion by F. johnsoniae. ChiA was secreted in soluble form by wild-type cells but remained cell associated in strains carrying mutations in any of the T9SS genes, gldK, gldL, gldM, gldNO, sprA, sprE, and sprT. Western blot and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses suggested that ChiA was proteolytically processed into two GH18 domain-containing proteins. Proteins secreted by T9SSs typically have conserved carboxy-terminal domains (CTDs) belonging to the TIGRFAM families TIGR04131 and TIGR04183. ChiA does not exhibit strong similarity to these sequences and instead has a novel CTD. Deletion of this CTD resulted in accumulation of ChiA inside cells. Fusion of the ChiA CTD to recombinant mCherry resulted in secretion of mCherry into the medium. The results indicate that ChiA is a soluble extracellular chitinase required for chitin utilization and that it relies on a novel CTD for secretion by the F. johnsoniae T9SS.

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Section: Discussionsupporting

confidence: 57%

Flavobacterium johnsoniae Chitinase ChiA Is Required for Chitin Utilization and Is Secreted by the Type IX Secretion System

Kharade

McBride

2013

Journal of Bacteriology

110

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“…The sites of transposon insertions were determined for 37 randomly selected motile nonspreading mutants as previously described (5,16,19,33). Six mutants had insertions in sprA (31), and two had insertions in secDF (32). Of the remaining 29 mutants, 16 had insertions in a 19.5-kbp gene that we designated sprB (Fig.…”

Section: Resultsmentioning

confidence: 99%

SprB Is a Cell Surface Component of the Flavobacterium johnsoniae Gliding Motility Machinery

2008

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Cells of the gliding bacterium Flavobacterium johnsoniae move rapidly over surfaces by an unknown mechanism. Transposon insertions in sprB resulted in cells that were defective in gliding. SprB is a highly repetitive 669-kDa cell surface protein, and antibodies against SprB inhibited the motility of wild-type cells. Polystyrene microspheres coated with antibodies against SprB attached to and were rapidly propelled along the cell surface, suggesting that SprB is one of the outermost components of the motility machinery. The movement of SprB along the cell surface supports a model of gliding motility in which motors anchored to the cell wall rapidly propel cell surface adhesins.

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“…4A, lane 15, and B, lane 15). SprB and GldJ are also absent or nearly absent in secDF mutant cells (23,25). SecDF may play a role in export across the cytoplasmic membrane, and the mislocalized proteins in the secDF mutant may be subject to degradation.…”

Section: Vol 193 2011mentioning

confidence: 99%

Flavobacterium johnsoniae sprB Is Part of an Operon Spanning the Additional Gliding Motility Genes sprC , sprD , and sprF

et al. 2011

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Cells of Flavobacterium johnsoniae move rapidly over surfaces by a process known as gliding motility. Gld proteins are thought to comprise the gliding motor that propels cell surface adhesins, such as the 669-kDa SprB. A novel protein secretion apparatus called the Por secretion system (PorSS) is required for assembly of SprB on the cell surface. Genetic and molecular analyses revealed that sprB is part of a seven-gene operon spanning 29.3 kbp of DNA. In addition to sprB, three other genes of this operon (sprC, sprD, and sprF) are involved in gliding. Mutations in sprB, sprC, sprD, and sprF resulted in cells that failed to form spreading colonies on agar but that exhibited some motility on glass in wet mounts. SprF exhibits some similarity to Porphyromonas gingivalis PorP, which is required for secretion of gingipain protease virulence factors via the P. gingivalis PorSS. F. johnsoniae sprF mutants produced SprB protein but were defective in localization of SprB to the cell surface, suggesting a role for SprF in secretion of SprB. The F. johnsoniae PorSS is involved in secretion of extracellular chitinase in addition to its role in secretion of SprB. SprF was not needed for chitinase secretion and may be specifically required for SprB secretion by the PorSS. Cells with nonpolar mutations in sprC or sprD produced and secreted SprB and propelled it rapidly along the cell surface. Multiple paralogs of sprB, sprC, sprD, and sprF are present in the genome, which may explain why mutations in sprB, sprC, sprD, and sprF do not result in complete loss of motility and suggests the possibility that semiredundant SprB-like adhesins may allow movement of cells over different surfaces.

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Mutations in Flavobacterium johnsoniae secDF Result in Defects in Gliding Motility and Chitin Utilization

Abstract: secDF mutants of Flavobacterium johnsoniae were deficient in gliding motility and chitin utilization. Cells of the mutants had reduced levels of GldJ protein, which is required for both processes. SecDF is similar to Escherichia coli SecD and SecF, which are involved in protein secretion.

Cited by 15 publications

References 29 publications

Flavobacterium johnsoniae Chitinase ChiA Is Required for Chitin Utilization and Is Secreted by the Type IX Secretion System

Flavobacterium johnsoniae Chitinase ChiA Is Required for Chitin Utilization and Is Secreted by the Type IX Secretion System

SprB Is a Cell Surface Component of the Flavobacterium johnsoniae Gliding Motility Machinery

Flavobacterium johnsoniae sprB Is Part of an Operon Spanning the Additional Gliding Motility Genes sprC , sprD , and sprF

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