Related Research Articles
The Phi11 Holin Family constitutes the Holin Superfamily I.
The Phage 21 S Family is a member of the Holin Superfamily II.
The T7 Holin family is a member of the Holin Superfamily II. Members of this family are predominantly found in Caudovirales and Proteobacteria. They typically have only 1 transmembrane segment (TMS) and vary from 60 to 130 amino acyl residues in length. A representative list of proteins belonging to this family can be found in the Transporter Classification Database.
The HP1 Holin Family is a member of the Holin Superfamily II. Proteins in this family are typically found to contain two transmembrane segments (TMSs) and range between 70 and 80 amino acyl residues (aas) in length. A representative list of proteins belonging to the HP1 holin family can be found in the Transporter Classification Database.
The Holin Superfamily III is a superfamily of integral membrane transport proteins. It is one of the seven different holin superfamilies in total. In general, these proteins are thought to play a role in regulated cell death, although functionality varies between families and individual members.
The putative actinobacterial holin-X (Hol-X) family was retrieved as a distant member of TC family 1.E.20, suggesting membership of the holin superfamily III. Most Hol-X proteins are less than 200 amino acyl residues (aas) in length and possess two transmembrane segments (TMSs). A representative list of proteins belonging to this family can be found in the Transporter Classification Database.
The Holin superfamily IV is a superfamily of integral membrane transport proteins. It is one of the seven different holin superfamilies in total.
The Holin superfamily V is a superfamily of integral membrane transport proteins. It is one of the seven different holin superfamilies in total. In general, these proteins are thought to play a role in regulated cell death, although functionality varies between families and individual members. The Holin superfamily V includes the TC families:
The Bacillus subtilis φ29 Holin Family is a group of transporters belonging to the Holin Superfamily IV. A representative list of members belonging to the φ29 holin family can be found in the Transporter Classification Database.
The Cph1 Holin Family is also called the CDD Holin 4 superfamily, but belongs to the Holin Superfamily IV as classified in the Transporter Classification Database (TCDB). A representative list of members belonging to the Cph1 family can be found in TCDB.
The Mycobacterial 4 TMS Phage Holin Family is a group of transporters belonging to Holin superfamily IV. A representative list of members belonging to the MP4 holin family can be found in the Transporter Classification Database.
The Holin Hol44 (Hol44) Family is a group of transporters belonging to the Holin Superfamily V. A representative list of proteins belonging to the Hol44 family from caudovirales and firmicutes can be found in the Transporter Classification Database.
The holin LLH family is a group of transporters belonging to the Holin superfamily VI. The Holin LLH family is found in Firmicutes and phage of Firmicutes as well as other bacteria. Members are fairly large, between 100 and 160 amino acyl residues in length, and have an N-terminal transmembrane segment (TMS). Some proteins, such as putative holin of Fusobacterium varium, may exhibit 2 TMSs. A representative list of proteins belonging to the Holin LLH family can be found in the Transporter Classification Database.
The Putative 3-4 TMS Transglycosylase-associated Holin Family is believed to be a group of holins that does not belong to one of the seven holin superfamilies. Homologues include thousands of diverse phage and bacterial proteins between 80 and 140 amino acyl residues (aas) in length that exhibit 3 to 4 transmembrane segments (TMSs). These proteins are holin-like in their size and topology and are designated 'Transglycosylase-associated', 'Putative holin', 'Phage-like transmembrane protein', 'YeaQ protein', etc. in the NCBI protein database. As of early 2016, they remain functionally uncharacterized. 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 the conserved domain database. A representative list of proteins belonging to the T-A Hol family can be found in the Transporter Classification Database.
The Putative Lactococcus lactis Holin (LLHol) Family consists of just a few proteins from Lactococcus lactis species and their phage. These proteins are small, between 61 and 78 amino acyl residues (aas) in length, and exhibit one or two transmembrane segments (TMSs). As of March 2016, LLHol proteins remain functionally uncharacterized. They are not demonstrably homologous to members of other holin families and thus do not belong to one of the seven holin superfamilies. A representative list of proteins belonging to the LLHol family can be found in the Transporter Classification Database.
The β-proteobacterial holin (BP-Hol) family is a small family that includes members derived from a number of Burkholderia phage as well as a Poloromonas species. As of April 3, 2016, this family belongs to the Holin superfamily II. Members of Saier Bioinformatics Lab at University of California, San Diego found that the BP-Hol family is most closely related to the T7 holin family. These proteins are of 60 to 110 amino acyl residues (aas) in length and exhibit 1 or 2 transmembrane segments (TMSs). Some are annotated as type II hollins and may be related to members of the T7 Holin family, although BP-Hol proteins remain functionally uncharacterized. A representative list of the proteins belonging to the BP-Hol family can be found in the Transporter Classification Database.
The Flp/Fap Pilin Putative Holin (FFPP-Hol) Family is a large diverse family with members from many bacterial phyla. Some members are annotated as Flp or Fap pilin subunits; others are identified as Holin BlyA family members. They range in size of 50 to 80 amino acyl residues (aas) with a single N-terminal transmembrane segment (TMS) although one member has 99 aas and 2 TMSs. Flp homologues are included in TCDB under TC# 3.A.7.13.1 (pXO1-63) and TC# 3.A.7.15.1 (Flp-1). As on March 2016, their precise functions appear to be unknown. A representative list of proteins belonging to the FFPP-Hol family can be found in the Transporter Classification Database.
The Brachyspira holin (B-Hol) Family consists of several proteins from the GTA holin of Brachyspira hyodysenteriae, which facilitates gene transfer agent-release to VSH-1 holin of Brachyspira pilosicoli. VSH-1 is thought to participate in cell lysis. These proteins range in size from about 85 to 145 amino acyl residues (aas) and exhibit between 2 and 4 transmembrane segments (TMSs). A representative list of proteins belonging to the B-Hol family can be found in the Transporter Classification Database.
The Putative 3 TMS Holin (3-Hol) Family is large, consisting of many members derived from proteobacteria and their phage, all of small size and usually with 3 transmembrane segments (TMSs). A representative list of the proteins belonging to this family can be found in the Transporter Classification Database. While many of the proteins belonging to this family are annotated in holins, they remain functionally uncharacterized.
The Putative Bacterial Archaeal Holin(BAH) Family consists of several uncharacterized proteins. However, these proteins were retrieved when functionally characterized holins from the T-A Hol family were BLASTED against the NCBI database, and thus may be related to the T-A Hol family. Most BAH proteins are between 125 and 140 amino acyl residues (aas) in length and exhibit 4 transmembrane segments (TMSs), although at least one putative holin is almost 260 aas long. A representative list of proteins belonging to the BAH family can be found in the Transporter Classification Database.
References
- ↑ Schmidt, C.; Velleman, M.; Arber, W. (1996-02-01). "Three functions of bacteriophage P1 involved in cell lysis". Journal of Bacteriology. 178 (4): 1099–1104. doi:10.1128/jb.178.4.1099-1104.1996. ISSN 0021-9193. PMC 177771 . PMID 8576044.
- ↑ Reddy, Bhaskara L.; Saier, Milton H. (2013-11-01). "Topological and phylogenetic analyses of bacterial holin families and superfamilies". Biochimica et Biophysica Acta (BBA) - Biomembranes. 1828 (11): 2654–2671. doi:10.1016/j.bbamem.2013.07.004. ISSN 0006-3002. PMC 3788059 . PMID 23856191.
- ↑ "1.E.4 The LydA Holin (LydA Holin) Family". Transporter Classification Database. Retrieved 2016-03-21.
As of 10 March 2016, this article is derived in whole or in part from Transporter Classification Database (TCDB). The copyright holder has licensed the content in a manner that permits reuse under CC BY-SA 3.0 and GFDL. All relevant terms must be followed.The original text was at "1.E.4 The LydA Holin (LydA Holin) Family"
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