HP1 holin family

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The HP1 Holin (HP1 Holin) Family (TC# 1.E.7 ) is a member of the Holin Superfamily II. [1] 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 NucE protein (TC# 1.E.25.2.1) in Serratia marcescens shows homology to phage holin proteins involved in releasing lysozyme to the peptidoglycan of Gram-negative bacteria. The protein contains two characteristic transmembrane segments (TMSs) with a positively charged C-terminus. When the nucC operon carrying the nucEDC genes is placed in the Escherichia coli chromosome, NucE functions as a holin. Additionally, NucE can complement lysis-defective bacteriophage mutants to allow for plaque formation and release of phage. Although NucE can function as a holin it is not involved in the transport of nuclease, an extracellular protein encoded by the nucA gene. [2] [3] [4]

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The Phi11 Holin Family constitutes the Holin Superfamily I.

The Holin superfamily II is a superfamily of putative pore-forming 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 II includes the TC families:

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 Lambda Holin S Family is a group of integral membrane transporter proteins belonging to the Holin Superfamily III. Members of this family generally consist of the characteristic three transmembrane segments (TMSs) and are of 110 amino acyl residues (aas) in length, on average. A representative list of members belonging to this family can be found in the Transporter Classification Database.

The Pseudomonas aeruginosa Hol Holin Family is a group of transporters belonging to the Holin Superfamily III.

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 Listeria Phage A118 Holin (Hol118) Family is a group of transporters belonging to the Holin Superfamily V. A representative list of proteins belonging to the Hol118 family can be found in the Transporter Classification Database.

The Mycobacterial 2 TMS Phage Holin Family is a group of transporters belonging to the Holin Superfamily VII. The Mycobactrerial 2 transmembrane segment (TMS) Holins have been identified and recognized by Catalao et al (2012). The Mycobacterium phage D29 gp11 protein is a holin that, upon expression, rapidly kills both E. coli and Mycobacterium smegmatis. Shortening gp11 from its C-terminus resulted in diminished cytotoxicity and smaller holes. The two TMSs at the N-terminus alone do not integrate into the cytoplasmic membrane and do not show toxicity. Fusion of the two TMSs and a small C-terminal coiled-coil region resulted in restoration of cell killing. The second TMS is dispensable for toxicity. The gp11 C-terminal region is therefore necessary but not sufficient for toxicity.

The T4 Holin Family is a group of putative pore-forming proteins that does not belong to one of the seven holin superfamilies. T-even phage such as T4 use a holin-endolysin system for host cell lysis. Although the endolysin of phage T4 encoded by the e gene was identified in 1961, the holin was not characterized until 2001. A representative list of proteins belonging to the T4 holin family can be found in the Transporter Classification Database.

The Lactococcus lactis Phage r1t Holin Family is a family of putative pore-forming proteins that typically range in size between about 65 and 95 amino acyl residues (aas) in length, although a few r1t holins have been found to be significantly larger. Phage r1t holins exhibit between 2 and 4 transmembrane segments (TMSs), with the 4 TMS proteins resulting from an intragenic duplication of a 2 TMS region. A representative list of the proteins belonging to the r1t holin family can be found in the Transporter Classification Database.

The Streptomyces aureofaciens Phage Mu1/6 Holin Family is a family of putative pore-forming holins between 80 and 90 amino acyl residues in length with 2 transmembrane segments (TMSs). A representative list of proteins belonging to this family can be found in the Transporter Classification Database.

The SPP1 Holin Family consists of proteins of between 90 and 160 amino acyl residues (aas) in length that exhibit two transmembrane segments (TMSs). SPP1 is a double-stranded DNA phage that infects the Gram-positive bacteria. Although annotated as holins, members of the SPP1 family are not yet functionally characterized. A representative list of proteins belonging to the SPP1 Holin family can be found in Transporter Classification Database.

The Mycobacterial 1 TMS Phage Holin Family was identified and recognized by Catalao et al. (2012). Members of this family are found in mycobacterial phage, exhibit a single transmembrane segment (TMSs), and are about 75 to 95 amino acyl residues in length. Although annotated as holins, members of this family are not yet functionally characterized. A representative list of proteins belonging to this family can be found in the Transporter Classification Database.

The Phage T1 Holin Family is represented in enterobacterial phages T1, RTP and F20, Klebsiella phage KP36, and Escherichia phage ADB-2. All of these possess a putative holin that share a high level of identity. Additionally, Gp9 of E. coli phage phiE49 is similar in sequence. These proteins are short, 55 to 71 amino acyl residues (aas) in length, and exhibit a single transmembrane segment (TMS). A representative list of proteins belonging to the T1 Holin family can be found in the Transporter Classification Database.

The Staphylococcusphage P68 Putative Holin Family consists of a single putative holin from Staphylococcus aureus phage P68 that is 92 amino acyl residues (aas) in length and exhibits 2 transmembrane segments (TMSs). While annotated as a holin, this protein has not been functionally characterized.[2]

The Mycobacterial Phage PBI1 Gp36 Holin Family consists of a single protein, Gp36 of Mycobacterial phage PBI1 identified by Castalao et al. (2012). Gp36 is 116 amino acyl residues (aas) in length and exhibits 2 transmembrane segments (TMSs). While annotated as a holin, this protein has not been functionally characterized.

The CaulobacterPhage Holin (CauHol) Family consists of several putative holins of 157 to 159 amino acyl residues (aas) in length that exhibit 2 transmembrane segments (TMSs). They derive from phage specific for Caulobacter species. These proteins are not functionally characterized. A representative list of proteins belonging to the CauHol family can be found in the Transporter Classification Database.

The Actinobacterial Phage Holin (APH) Family is a fairly large family of proteins between 105 and 180 amino acyl residues in length, typically exhibiting a single transmembrane segment (TMS) near the N-terminus. A representative list of proteins belonging to the APH family can be found in the Transporter Classification Database.

References

  1. ↑ 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.
  2. ↑ Berkmen, M.; Benedik, M. J.; Bläsi, U. (1997-10-01). "The Serratia marcescens NucE protein functions as a holin in Escherichia coli". Journal of Bacteriology. 179 (20): 6522–6524. doi:10.1128/jb.179.20.6522-6524.1997. ISSN   0021-9193. PMC   179574 . PMID   9335307.
  3. ↑ Jin, S.; Chen, Y.; Christie, G. E.; Benedik, M. J. (1996-02-23). "Regulation of the Serratia marcescens extracellular nuclease: positive control by a homolog of P2 Ogr encoded by a cryptic prophage". Journal of Molecular Biology. 256 (2): 264–278. doi:10.1006/jmbi.1996.0084. ISSN   0022-2836. PMID   8594195.
  4. ↑ Strych, U.; Dai, W.; Benedik, M. J. (1999-05-01). "The NucE and NucD lysis proteins are not essential for secretion of the Serratia marcescens extracellular nuclease". Microbiology. 145 ( Pt 5) (5): 1209–1216. doi: 10.1099/13500872-145-5-1209 . ISSN   1350-0872. PMID   10376837.

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.7 The HP1 Holin (HP1 Holin) Family"


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