HU Protein Affects Transcription of Surface Polysaccharide Synthesis Genes in
            <i>Porphyromonas gingivalis</i>

Alberti-Segui, Christine; Arndt, Annette; Cugini, Carla; Priyadarshini, Richa; Davey, Mary E.

doi:10.1128/jb.00106-10

Cited by 23 publications

(43 citation statements)

References 59 publications

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“…The annotation in the Comprehensive Microbial Resource (CMR) database predicted that genes PG0106 through PG0120 were part of an operon, and our previous studies confirmed this annotation (20,26). As previously reported (25), a large (77-bp) inverted repeat (77bpIR) region is located 5= to PG0106. This element and the genes flanking the 77bpIR region are shown in Fig.…”

Section: Resultssupporting

confidence: 63%

“…The loop itself consists of 520 bp. Recently, we demonstrated that the HU protein (PG0121), which is encoded at the 3= end of the locus, binds to the 77bpIR element with high affinity in vitro, and we biochemically characterized the interaction (25,27).…”

Section: Resultsmentioning

confidence: 99%

“…The serotype-specific rabbit antiserum to P. gingivalis W83 and a rabbit polyclonal antibody to PG0121 have been described previously (25,26). The A-LPS-specific monoclonal antibody 1B5 was obtained from Michael Curtis, Queen Mary University of London, London, England, and the O-LPS-specific monoclonal antibody 7F12 was obtained from Richard Darveau, University of Washington, Seattle, WA.…”

Section: Methodsmentioning

confidence: 99%

“…Previously, we showed by Northern analysis that the K-antigen locus encodes a large polycistronic message (PG0104 to PG0121) encompassing a 77-bp inverted repeat (77bpIR) region (25,26), and we determined that the histone-like protein HU (PG0121), which is encoded at the 3= end of the transcript, binds to the 77-bp sequence (27). Our working model has been that this interaction is involved in regulating transcription and/or RNA stability.…”

mentioning

confidence: 99%

“…Just recently, Ltp1 was shown to inactivate (dephosphorylate) the tyrosine kinase Ptk1, which in turn was shown to control levels of exopolysaccharide production in both strain 33277 and W83 (24), showing that this tyrosine kinase modulates production and export of extracellular polysaccharide in P. gingivalis. The second regulatory mechanism that has been identified is the DNA-BII protein HU ␤-subunit (PG0121); specifically, genes in both the K-antigen synthesis locus and the A-LPS locus are downregulated in a PG0121 mutant (25,26).…”

mentioning

confidence: 99%

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Deletion of a 77-Base-Pair Inverted Repeat Element Alters the Synthesis of Surface Polysaccharides in Porphyromonas gingivalis

et al. 2015

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Bacterial cell surface glycans, such as capsular polysaccharides and lipopolysaccharides (LPS), influence host recognition and are considered key virulence determinants. The periodontal pathogen Porphyromonas gingivalis is known to display at least three different types of surface glycans: O-LPS, A-LPS, and K-antigen capsule. We have shown that PG0121 (in strain W83) encodes a DNABII histone-like protein and that this gene is transcriptionally linked to the K-antigen capsule synthesis genes, generating a large ϳ19.4-kb transcript (PG0104-PG0121). Furthermore, production of capsule is deficient in a PG0121 mutant strain. In this study, we report on the identification of an antisense RNA (asRNA) molecule located within a 77-bp inverted repeat (77bpIR) element located near the 5= end of the locus. We show that overexpression of this asRNA decreases the amount of capsule produced, indicating that this asRNA can impact capsule synthesis in trans. We also demonstrate that deletion of the 77bpIR element and thereby synthesis of the large 19.4-kb transcript also diminishes, but does not eliminate, capsule synthesis. Surprisingly, LPS structures were also altered by deletion of the 77bpIR element, and reactivity to monoclonal antibodies specific to both O-LPS and A-LPS was eliminated. Additionally, reduced reactivity to these antibodies was also observed in a PG0106 mutant, indicating that this putative glycosyltransferase, which is required for capsule synthesis, is also involved in LPS synthesis in strain W83. We discuss our finding in the context of how DNABII proteins, an antisense RNA molecule, and the 77bpIR element may modulate expression of surface polysaccharides in P. gingivalis. IMPORTANCEThe periodontal pathogen Porphyromonas gingivalis displays at least three different types of cell surface glycans: O-LPS, A-LPS, and K-antigen capsule. We have shown using Northern analysis that the K-antigen capsule locus encodes a large transcript (ϳ19.4 kb), encompassing a 77-bp inverted repeat (77bpIR) element near the 5= end. Here, we report on the identification of an antisense RNA (asRNA) encoded within the 77bpIR. We show that overexpression of this asRNA or deletion of the element decreases the amount of capsule. LPS structures were also altered by deletion of the 77bpIR, and reactivity to monoclonal antibodies to both O-LPS and A-LPS was eliminated. Our data indicate that the 77bpIR element is involved in modulating both LPS and capsule synthesis in P. gingivalis. E ncapsulation is a well-known mechanism that protects pathogenic bacteria from clearance by host immune defenses (1). This reduction in clearance can lead to persistent survival and thereby long-term interplay between the bacterium and host. Capsules not only reduce the ability of the host effectors to gain access to the bacterial cell but also mask the cell surface and thereby modulate the host's response to the bacterium. This model is supported by studies showing that encapsulated bacteria have an advantage in immune evasion (2). Synthesis of a...

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Section: Resultssupporting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Deletion of a 77-Base-Pair Inverted Repeat Element Alters the Synthesis of Surface Polysaccharides in Porphyromonas gingivalis

et al. 2015

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Effects of the histone-like protein HU on cellulose degradation and biofilm formation of Cytophaga hutchinsonii

Guan

Wang

Gao

et al. 2018

Appl Microbiol Biotechnol

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Cytophaga hutchinsonii, belonging to Bacteroidetes, is speculated to use a novel cell-contact mode to digest cellulose. In this study, we identified a histone-like protein HU, CHU_2750, in C. hutchinsonii, whose transcription could be induced by crystalline but not amorphous cellulose. We constructed a CHU_2750-deleted mutant and expressed CHU_2750 in Escherichia coli to study the gene's functions. Our results showed that although the deletion of CHU_2750 was not lethal to C. hutchinsonii, the mutant displayed an abnormal filamentous morphology, loose nucleoid, and obvious defects in the degradation of crystalline cellulose and cell motility. Further study indicated that the mutant displayed significantly decreased cell surface and intracellular endoglucanase activities but with β-glucosidase activities similar to the wild-type strain. Analyses by real-time quantitative PCR revealed that the transcription levels of many genes involved in cellulose degradation and/or cell motility were significantly downregulated in the mutant. In addition, we found that CHU_2750 was important for biofilm formation of C. hutchinsonii. The main extracellular components of the biofilm were analyzed, and the results showed that the mutant yielded significantly less exopolysaccharide but more extracellular DNA and protein than the wild-type strain. Collectively, our findings demonstrated that CHU_2750 is important for cellulose degradation, cell motility, and biofilm formation of C. hutchinsonii by modulating transcription of certain related genes, and it is the first identified transcriptional regulator in these processes of C. hutchinsonii. Our study shed more light on the mechanisms of cellulose degradation, cell motility, and biofilm formation by C. hutchinsonii.

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Interleukin-1β is internalised by viable Aggregatibacter actinomycetemcomitans biofilm and locates to the outer edges of nucleoids

et al. 2012

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HU Protein Affects Transcription of Surface Polysaccharide Synthesis Genes in Porphyromonas gingivalis

Cited by 23 publications

References 59 publications

Deletion of a 77-Base-Pair Inverted Repeat Element Alters the Synthesis of Surface Polysaccharides in Porphyromonas gingivalis

Deletion of a 77-Base-Pair Inverted Repeat Element Alters the Synthesis of Surface Polysaccharides in Porphyromonas gingivalis

Effects of the histone-like protein HU on cellulose degradation and biofilm formation of Cytophaga hutchinsonii

Interleukin-1β is internalised by viable Aggregatibacter actinomycetemcomitans biofilm and locates to the outer edges of nucleoids

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