1.E.7 The HP1 Holin (HP1 Holin) Family

See 1.E for a generalized description of Holins.

The NucE protein 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 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.

 


This family belongs to the Holin II Superfamily .
 

References:

Berkmen, M., M.J. Benedik, and U. Bläsi. (1997). The Serratia marcescens NucE protein functions as a holin in Escherichia coli. J. Bacteriol. 179: 6522-6524.
Jin, S., Y. Chen, G.E. Christie and M.J. Benedik (1996). Regulation of the Serratia marcescens extracellular nuclease: positive control by a homolog of P2 Ogr encoded by a cryptic prophage. J. Mol. Biol. 256: 264-278.
Strych U., W. Dai, and M.J. Benedik (1999). The NucE and NucD lysis proteins are not essential for secretion of the Serratia marcescens extracellular nuclease. Microbiology 145: 1209-1216.
Examples:

TC#NameOrganismal TypeExample
1.E.7.1.1

Holin of 78 aas and 1 - 3 TMSs.

Holin Haemophilus influenzae phage HP1; spP51727)

 
1.E.7.1.2

Holin of 74 aas and 1 TMS.

Proteobacteria

Holin of Haemophilus somnus

 
1.E.7.1.3

Holin of 68 aas and 1 TMS.

Holin of Mannheimia haemolytica

 
1.E.7.1.4

Holin of 75 aas and 1 TMS

Holin of Rodentibacter trehalosifermentans

 
Examples:

TC#NameOrganismal TypeExample
1.E.7.2.1

phage pg24 protein of 80 aas and 1 TMS

Phage

gp24 of Burkholderia phage phi644-2

 
1.E.7.2.2

Holin of 83 aas and 1 TMS.

Holin of Azomonas agilis

 
1.E.7.2.3

Holin of 96 aas and 1 TMS

Holin of Thauera butanivorans

 
1.E.7.2.4

Holin of 66 aas and 1 TMS

Holin of Siphoviridae sp. (Human Metagenome)

 
1.E.7.2.5

Holin of 80 aas and 1 TMS

Holin of Comamonas odontotermitis

 
1.E.7.2.6

Holin of 67 aas and 1 TMS

Holin of Enterobacter cloacae

 
1.E.7.2.7

Holin of 78 aas and 2 TMSs

Holin of Acinetobacter soli