1.E.54 The Gene Transfer Agent-release Holin (GTA-Hol) Family 

The gene transfer agent of Rhodobacter capsulatus (RcGTA) is a bacteriophage-like genetic element with the sole known function of horizontal gene transfer. Homologues of RcGTA genes are present in many members of the alphaproteobacteria and may serve an important role in microbial gene transfer between organisms. Transcription of RcGTA genes is induced as cultures enter the stationary phase. Westbye et al. 2013 identified the promoter of the first gene in the RcGTA structural gene cluster and showed that gene transduction frequencies depend on the growth medium.  Millimolar concentrations of phosphate posttranslationally inhibit the lysis-dependent release of RcGTA from cells in both a complex medium and a defined medium.  Cell lysis requires the genes rcc00555 and rcc00556, which were expressed and studied in Escherichia coli to demonstrate their  functions as an endolysin and holin, respectively. Production of RcGTA is regulated by host systems, including the histidine kinase, CckA, which is required for maximal expression of rcc00555 and for maturation of RcGTA to yield gene transduction-functional particles.


 

References:

Westbye, A.B., M.M. Leung, S.M. Florizone, T.A. Taylor, J.A. Johnson, P.C. Fogg, and J.T. Beatty. (2013). Phosphate concentration and the putative sensor kinase protein CckA modulate cell lysis and release of the Rhodobacter capsulatus gene transfer agent. J. Bacteriol. 195: 5025-5040.

Examples:

TC#NameOrganismal TypeExample
1.E.54.1.1

Gene Transfer Agent (GTA) holin of 164 aas with 3 TMSs in a 1 + 2 TMS arrangement.  Involved in GTA release from cells in stationary phase (Westbye et al. 2013).

Proteobacteria

GTA holin of Rhodobacter capsulatus

 
1.E.54.1.2

Putative holin of 195 aas

Proteobacteria

Putative holin of Rhodospirillum photometricum

 
1.E.54.1.3

Putative holin of 186 aas

Proteobacteria

Holin homologue of Saccharophagus degradans

 
1.E.54.1.4

Putative holin of 181 aas of the DUF3154 family.

Proteobacteria

Putative holin of Rubelimicrobium thermophilum

 
1.E.54.1.5

Putative holin of 177 aas and 2 TMSs.

Proteobacteria

Putative holin of Rhodospirillum photometricum

 
Examples:

TC#NameOrganismal TypeExample
1.E.54.2.1

Putative holin of 134 aas and 2 TMSs.

Proteobacteria

Putative holin of Desulfovibrio desulfuricans

 
1.E.54.2.2

Putative holin of 136 aas and 2 TMSs.

Proteobacteria

Putative holin of Vibrio splendidus

 
1.E.54.2.3

Putative holin of 113 aas and 2 TMSs

Proteobacteria

Putative holin of Puniceispirillum marinum

 
1.E.54.2.4

Putative holin of 150 aas and 2 TMSs

Proteobacteria

Putative holin of Pseudoalteromonas tunicata

 
1.E.54.2.5

Putative holin of 196 aas and 2 or 3 TMSs.

Proteobacterial virus

Putative holin of Salmonella phage ViI

 
1.E.54.2.6

Putative holin of 121 aas and 2 TMSs.

Proteobacteria

Putative holin of Pelagibacter phage HTVC011P

 
Examples:

TC#NameOrganismal TypeExample
1.E.54.4.1

Gp21 protein of 145 aas and 2-3 TMSs

Gp21 of Cellulophaga phage phi48:2

 
1.E.54.4.2

Putative holin of 148 aas and 2 TMSs

Putative holin of Pseudoalteromonas haloplanktis

 
1.E.54.4.3

Uncharacterized protein of 149 aas and 2 putative TMSs

UP of Desulfatibacillum alkenivorans

 
1.E.54.4.4

Uncharacterized protein of 168 aas and 2 - 3 TMSs

UP of Teredinibacter turnerae

 
1.E.54.4.5

Uncharaterized protein of 145 aas and 2 TMSs

UP of Vibrio azureus

 
1.E.54.4.6

Uncharacterized protein of 132 aas and 2 TMSs

UP of Pseudoalteromonas piscicida

 
1.E.54.4.7

Uncharacterized protein of 87 aas and 2 TMSs

UP of Aliivibrio salmonicida (Vibrio salmonicida)

 
Examples:

TC#NameOrganismal TypeExample
1.E.54.5.1

Uncharacterized protein of 137 aas and 3 TMSs

UP of Novosphingobium aromaticivorans

 
1.E.54.5.2

Uncharacterized protein of 144 aas and 2 - 3 TMSs

UP of Marinobacter nanhaiticus