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1.E.43 The Putative 3-4 TMS Transglycosylase-associated Holin (T-A Hol) Family

Thousands of diverse phage and bacterial proteins of 80-140aas with 3-4 TMSs prove to be homologous. They are holin-like and are designated 'Transglycosylase-associated', 'Putative holin' 'Phage-like transmembrane protein', 'YeaQ protein', etc. in the NCBI protein database. Their functions appear to be unknown. They derive from a wide range of bacterial and archaeal phyla including both Gram-negative and Gram-positive bacteria.  These proteins are related to the RDD family in CDD (> 15 SD with the GSAT program with 20,000 random shuffles). 

The RDD (pfam06271) family includes members with these highly conserved residues Arg, Asp and Asp, hence the name. This region contains the first two predicted TMSs of a total of 3 or 4 TMSs. The R is at the N-terminus of the first TMS and the first D is in the middle of this helix. This region of the protein may be involved in the transport of an unknown set of ligands (A Bateman, pers. observation; see CDD). Some members are fused to other domains of recognized function.

References associated with 1.E.43 family:

Hug, L.A., B.J. Baker, K. Anantharaman, C.T. Brown, A.J. Probst, C.J. Castelle, C.N. Butterfield, A.W. Hernsdorf, Y. Amano, K. Ise, Y. Suzuki, N. Dudek, D.A. Relman, K.M. Finstad, R. Amundson, B.C. Thomas, and J.F. Banfield. (2016). A new view of the tree of life. Nat Microbiol 1: 16048. 27572647