CidA/LrgA holin

The CidA/LrgA Holin (CidA/LrgA Holin) Family (TC# 1.E.14) is a group of proteins named after CidA (TC# 1.E.14.1.2) and LrgA (TC# 1.E.14.1.1) of Staphylococcus aureus. CidA and LrgA are homologous holin and anti-holin proteins, each with 4 putative transmembrane segments (TMSs).[1] Members of the CidA/LrgA holin family also include putative murine hydrolase exporters from a wide range of Gram-positive and Gram-negative bacteria as well as archaea. Most CidA/LrgA holin family proteins vary in size between 100 and 160 amino acyl residues (aas) in length although a few are larger.

Function

It has been proposed that CidA and CidB (23% and 32% identical to LrgA and LrgB, respectively) are involved in programmed cell death in a process that is analogous to apoptosis in eukaryotes.[2] These proteins are known to regulate and influence biofilm formation by releasing DNA from lysed cells which contributes to the biofilm matrix. CidA, a 131 aa protein with 4 putative TMSs, is believed to be the holin which exports the autolysin CidB, while LrgA may be an anti-holin, a protein that binds and inhibits holin activity. If this is a general mechanism for programmed cell death, this would explain their near ubiquity in the prokaryotic world.

Expression

The cidABC operon is activated by CidR in the presence of acetic acid.[3] Both CidAB and LrgAB affect biofilm formation, oxidative stress, stationary phase survival and antibiotic tolerance in a reciprocal fashion, and their genes are regulated by the LytSR two component regulatory system.[4] Microfluidic techniques have been used to follow gene expression temporally and spatially during biofilm formation, revealing that both cidA and lrgA are expressed mostly in the interior of tower structures in the biofilms, regulated by oxygen availability.[5] Analogous proteins may be linked to competence in S. mutants.[6]

See also

Further reading

References

  1. ↑ Ranjit, Dev K.; Endres, Jennifer L.; Bayles, Kenneth W. (2011-05-01). "Staphylococcus aureus CidA and LrgA proteins exhibit holin-like properties". Journal of Bacteriology 193 (10): 2468–2476. doi:10.1128/JB.01545-10. ISSN 1098-5530. PMC 3133170. PMID 21421752.
  2. ↑ Bayles, Kenneth W. (2003-07-01). "Are the molecular strategies that control apoptosis conserved in bacteria?". Trends in Microbiology 11 (7): 306–311. ISSN 0966-842X. PMID 12875813.
  3. ↑ Yang, Soo-Jin; Rice, Kelly C.; Brown, Raquel J.; Patton, Toni G.; Liou, Linda E.; Park, Yong Ho; Bayles, Kenneth W. (2005-09-01). "A LysR-type regulator, CidR, is required for induction of the Staphylococcus aureus cidABC operon". Journal of Bacteriology 187 (17): 5893–5900. doi:10.1128/JB.187.17.5893-5900.2005. ISSN 0021-9193. PMC 1196168. PMID 16109930.
  4. ↑ Sharma-Kuinkel, Batu K.; Mann, Ethan E.; Ahn, Jong-Sam; Kuechenmeister, Lisa J.; Dunman, Paul M.; Bayles, Kenneth W. (2009-08-01). "The Staphylococcus aureus LytSR two-component regulatory system affects biofilm formation". Journal of Bacteriology 191 (15): 4767–4775. doi:10.1128/JB.00348-09. ISSN 1098-5530. PMC 2715716. PMID 19502411.
  5. ↑ Moormeier, Derek E.; Endres, Jennifer L.; Mann, Ethan E.; Sadykov, Marat R.; Horswill, Alexander R.; Rice, Kelly C.; Fey, Paul D.; Bayles, Kenneth W. (2013-06-01). "Use of microfluidic technology to analyze gene expression during Staphylococcus aureus biofilm formation reveals distinct physiological niches". Applied and Environmental Microbiology 79 (11): 3413–3424. doi:10.1128/AEM.00395-13. ISSN 1098-5336. PMC 3648040. PMID 23524683.
  6. ↑ Ahn, Sang-Joon; Qu, Ming-Da; Roberts, Elisha; Burne, Robert A.; Rice, Kelly C. (2012-01-01). "Identification of the Streptococcus mutans LytST two-component regulon reveals its contribution to oxidative stress tolerance". BMC microbiology 12: 187. doi:10.1186/1471-2180-12-187. ISSN 1471-2180. PMC 3507848. PMID 22937869.

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