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2.A.122 The LrgB/CidB Holin-like Glycolate/Glycerate Transporter (LrgB/CidB/GGT) Family

CidA and LrgA are a putative holin/antiholin pair in Staphylococcus aureus. LrgB is LrgA-associated (lrgA and lrgB are translationally coupled) while CidB is CidA-associated (cidA and cidB are similarly translationally coupled). Both have been reported to play a role in cell wall hydrolysis, possibly by regulating murein hydrolase export.  The cidABC operon is controlled by CidR, encoded adjacent to the cidABC operon, and the lrgABC operon is controlled by LrgR, encoded upstream of the lrgABC operon.  Cell lysis results in response to acetic acid accumulation in the medium (Yang et al. 2005)

A longer homologue of the bacterial LrgB has been shown to be the plastidic glycolate glycerate transporter, PLGG1, of 512 aas and 12 TMSs in Arabidopsis thaliana (Pick et al. 2013).  The last 5 TMSs are homologous to the 5 TMSs in several CidB and LrgB proteins of bacteria (see proteins 2.A.122.1.1 and 1.2). This plant protein may represent a fusion of the bacterial LrgA and LrgB proteins (Wang and Bayles 2013).  Because of this function, it appears that at least this plant protein of 12 TMSs must be a secondary carrier.

References associated with 2.A.122 family:

Ahn, S.J., K.C. Rice, J. Oleas, K.W. Bayles, and R.A. Burne. (2010). The Streptococcus mutans Cid and Lrg systems modulate virulence traits in response to multiple environmental signals. Microbiology 156: 3136-3147. 20671018
Chen, Y., K. Gozzi, F. Yan, and Y. Chai. (2015). Acetic Acid Acts as a Volatile Signal To Stimulate Bacterial Biofilm Formation. MBio 6: e00392. 26060272
Chu, X., R. Xia, N. He, and Y. Fang. (2013). Role of Rot in bacterial autolysis regulation of Staphylococcus aureus NCTC8325. Res. Microbiol. 164: 695-700. 23774059
Pick, T.R., A. Bräutigam, M.A. Schulz, T. Obata, A.R. Fernie, and A.P. Weber. (2013). PLGG1, a plastidic glycolate glycerate transporter, is required for photorespiration and defines a unique class of metabolite transporters. Proc. Natl. Acad. Sci. USA 110: 3185-3190. 23382251
Wang, J. and K.W. Bayles. (2013). Programmed cell death in plants: lessons from bacteria? Trends Plant Sci. 18: 133-139. 23083702
Yang, S.J., K.C. Rice, R.J. Brown, T.G. Patton, L.E. Liou, Y.H. Park, and K.W. Bayles. (2005). A LysR-type regulator, CidR, is required for induction of the Staphylococcus aureus cidABC operon. J. Bacteriol. 187: 5893-5900. 16109930
Yang, Y., H. Jin, Y. Chen, W. Lin, C. Wang, Z. Chen, N. Han, H. Bian, M. Zhu, and J. Wang. (2012). A chloroplast envelope membrane protein containing a putative LrgB domain related to the control of bacterial death and lysis is required for chloroplast development in Arabidopsis thaliana. New Phytol 193: 81-95. 21916894