A 13-kDa Protein with a Helix–Turn–Helix Motif Is Encoded by Bacterial Operons Related to the SRP Pathway

Samuelsson, Tore; Macao, Bertil; Bölske, Göran

doi:10.1006/bbrc.1997.6199

Cited by 8 publications

(13 citation statements)

References 21 publications

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“…Prior literature on YlxM suggested that it functions as a transcriptional regulator of SRP components (20,23). We found that this is not the case in S. mutans.…”

Section: Discussioncontrasting

confidence: 48%

“…The genomes of the Gram-negative coccus Veillonella parvula and the nonfirmicute Gram-negative organisms Fusobacterium nucleatum and Thermovirga lienii also contain ylxM. ylxM is almost always located in immediate proximity to genes encoding SRP components, either ffh or ftsY (20) and sometimes both (Fig. S2).…”

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confidence: 99%

“…While the existence of ylxM has been recognized for some time, it has not been widely studied and no function has yet been established (20)(21)(22)(23). First reported in Mycoplasma mycoides, it was predicted to encode a 13-kDa protein with a helix-turn-helix (HTH) domain that might act as a transcriptional regulator of SRP components (20).…”

mentioning

confidence: 99%

“…First reported in Mycoplasma mycoides, it was predicted to encode a 13-kDa protein with a helix-turn-helix (HTH) domain that might act as a transcriptional regulator of SRP components (20). Subsequently, an S. mutans strain lacking ylxM demonstrated a modest growth defect in comparison to the growth of the parental strain (19).…”

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confidence: 99%

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YlxM Is a Newly Identified Accessory Protein That Influences the Function of Signal Recognition Particle Pathway Components in Streptococcus mutans

Williams

Crowley

Hasona

et al. 2014

Journal of Bacteriology

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Streptococcus mutans is a cariogenic oral pathogen whose virulence is determined largely by its membrane composition. The signal recognition particle (SRP) protein-targeting pathway plays a pivotal role in membrane biogenesis. S. mutans SRP pathway mutants demonstrate growth defects, cannot contend with environmental stress, and exhibit multiple changes in membrane composition. This study sought to define a role for ylxM, which in S. mutans and numerous other bacteria resides directly upstream of the ffh gene, encoding a major functional element of the bacterial SRP. YlxM was observed as a produced protein in S. mutans. Its predicted helix-turn-helix motif suggested that it has a role as a transcriptional regulator of components within the SRP pathway; however, no evidence of transcriptional regulation was found. Instead, capture enzyme-linked immunosorbent assay (ELISA), affinity chromatography, and bio-layer interferometry (BLI) demonstrated that S. mutans YlxM interacts with the SRP components Ffh and small cytoplasmic RNA (scRNA) but not with the SRP receptor FtsY. In the absence of FtsY, YlxM increased the GTP hydrolysis activity of Ffh alone and in complex with scRNA. However, in the presence of FtsY, YlxM caused an overall diminution of net GTPase activity. Thus, YlxM appears to modulate GTP hydrolysis, a process necessary for proper recycling of SRP pathway components. The presence of YlxM conferred a significant competitive growth advantage under nonstress and acid stress conditions when wild-type and ylxM mutant strains were cultured together. Our results identify YlxM as a component of the S. mutans SRP and suggest a regulatory function affecting GTPase activity.

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“…Prior literature on YlxM suggested that it functions as a transcriptional regulator of SRP components (20,23). We found that this is not the case in S. mutans.…”

Section: Discussioncontrasting

confidence: 48%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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YlxM Is a Newly Identified Accessory Protein That Influences the Function of Signal Recognition Particle Pathway Components in Streptococcus mutans

Williams

Crowley

Hasona

et al. 2014

Journal of Bacteriology

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“…In Bacillus subtilis (Honda et al, 1993) this operon encodes YlxM, a putative 13.2 kDa protein of unknown function which displays no significant homology to other known proteins in databases. YlxM contains helix-turn-helix motifs characteristic of DNA-binding proteins (Samuelsson et al, 1997). The other protein in the operon is Ffh, the fifty-four kDa subunit homologue of the eukaryotic signal recognition particle (SRP), a chaperonin which is also found in Escherichia coli and is involved in protein translocation and membrane biogenesis (reviewed by Luirink & Dobberstein, 1994).…”

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confidence: 99%

Streptococcus mutans ffh, a gene encoding a homologue of the 54 kDa subunit of the signal recognition particle, is involved in resistance to acid stress

et al. 1999

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The ability of Streptococcus mutans, a bacterial pathogen associated with dental caries, t o tolerate rapid drops in plaque pH (acidurance), is considered an important virulence factor. To study this trait, Tn917 mutants of 5. mutans strain JH1005 which display acid sensitivity have been isolated and partially characterized. In this paper, the characterization of one of these mutants, AS1 7, is reported. Preliminary sequence analysis revealed that the transposon insertion in AS17 occurred in the intergenic region of a two-gene locus which has been named sat for secretion and acid tolerance. This locus displays a high degree of homology t o the y/xM-ffh operon of Bacillus subtik The sat+ locus was cloned by complementation of a conditional Escherichia coli ffh mutant with an 5. mutans genomic library. Sequencing of the complementing clone identified the intact yIxM and #%i genes as well as a partial ORF with homology t o the proU/opuAC gene of B. subtilis which encodes the binding protein of the ProU/OpuA osmoregulated glycine betaine transport system. RNA dot blot experiments indicated steady-state levels of ffh mRNA in the mutant that were approximately eightfold lower compared to parental levels. This suggests a partial polar effect of the sat=l::Tn917 mutation on ffh expression. Upon acid shock (pH 5)# wild-type ffh mRNA levels were found t o increase approximately four-to eightfold compared to unstressed (pH 7.5) levels. Mutant levels remained unaltered under the same conditions. Experiments designed to investigate the origins of the acid-sensitivity of the mutant revealed a lack of an acid-adaptiveholerance response. Assays of proton-extruding ATPase (H+/ATPase) specific activity measured with purified membranes derived from acidAshocked AS17 showed twofold lower levels compared to the parent strain. Also, AS17 was found to be unable t o ferment sorbitol although it was able t o grow in glucose and a variety of other sugar substrates. These findings suggest that Ffh may be involved in the maintenance of a functional membrane protein composition during adaptation of S. mutans t o changing environmental conditions. Abbreviations: ATR, acid tolerance response; GSP, general secretory pathway; SRP, signal recognition particle. KeywordsThe CenBank accession number for the DNA sequence of the 3 kb DNA fragment containing the y/xM-ffh genes is U88582. INTRODUCTIONStreptococcus mutans plays a major role in the aetiology of human dental caries. This bacterium is able to demineralize dental enamel by generation of a localized acidic environment in plaque by rapid glycolysis of dietary sugars to lactic acid. In addition to its acidogenicity, S. mutans is able to tolerate exposure to continual and rapid cycles of acid shock. In vivo pH measurements have demonstrated that the pH of plaque can drop from pH 7.0 to values ranging from 3.0 to 4.0 in less than 20 min following the intake of carbohydrates (Imfeld & Lutz, 1980;Yamada et al., 1980;Mormann & Muhlemann, 1981 ; Schachtele & Harlander, 1984;Jensen & Wefel, 1989). E...

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Characterization of a Unique Gene ORF135 from Helicoverpa Armigera Single Nucleocapsid Nucleopolyhedrovirus

Shang

Liu

et al. 2006

Virus Genes

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The ORF135 of Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HearSNPV)(Ha135) is one of the 20 genes that are unique to HearSNPV. Computer-assisted analysis revealed that four potential post translation modification sites, four transcription factor associated domains and a DNA binding protein domain were found in Ha135 amino acid sequence. Northern blot analysis of Ha135 indicated that Ha135 transcript was detected at 12 h.p.i. and remained detectable at up to 122 h.p.i. RT-PCR method was used to understand the temporal regulation of the transcript at earlier stages, the result showed that the Ha135 transcript was detected as early as 3 h p.i. suggesting that Ha135 was an early gene, which is in agreement with the early promoter motifs. The Ha135 protein was also detected at 12 h.p.i and remained detectable until 122 h.p.i. by western blot using an anti-Ha135 antiserum. The product of Ha135 was found to be about 29 kDa, bigger than the predicted 24 kDa molecular weight, suggesting that post translational modification of the Ha135 protein occur in host cells. The subcellular location was studied using EGFP-Ha135, which suggested that the Ha135 protein is primarily localized in the nucleus, which is compatible with several functional domains present in Ha135 amino acid sequence. Together, these results suggest the possibility that HearSNPV ORFI35 might be involved in viral DNA transcription and/or replication.

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A 13-kDa Protein with a Helix–Turn–Helix Motif Is Encoded by Bacterial Operons Related to the SRP Pathway

Cited by 8 publications

References 21 publications

YlxM Is a Newly Identified Accessory Protein That Influences the Function of Signal Recognition Particle Pathway Components in Streptococcus mutans

YlxM Is a Newly Identified Accessory Protein That Influences the Function of Signal Recognition Particle Pathway Components in Streptococcus mutans

Streptococcus mutans ffh, a gene encoding a homologue of the 54 kDa subunit of the signal recognition particle, is involved in resistance to acid stress

Characterization of a Unique Gene ORF135 from Helicoverpa Armigera Single Nucleocapsid Nucleopolyhedrovirus

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