Protein Family Models

This HMM identifies a region shared by DNA topoisomerases of different types, including ATP-independent (type I) topoisomerases such as TopA and TopB, and ATP-dependent reverse gyrases.

Date:

2024-10-16

This is a conserved region from DNA primase. This corresponds to the Toprim domain common to DnaG primases, topoisomerases, OLD family nucleases and RecR proteins [1]. Both DnaG motifs IV and V are present in the alignment, the DxD (V) motif may be involved in Mg2+ binding and mutations to the conserved glutamate (IV) completely abolish DnaG type primase activity [1]. DNA primase EC:2.7.7.6 is a nucleotidyltransferase it synthesises the oligoribonucleotide primers required for DNA replication on the lagging strand of the replication fork; it can also prime the leading stand and has been implicated in cell division [2]. This family also includes the atypical archaeal A subunit from type II DNA topoisomerases [4]. Type II DNA topoisomerases catalyse the relaxation of DNA supercoiling by causing transient double strand breaks. [1]. 9722641. Toprim--a conserved catalytic domain in type IA and II topoisomerases, DnaG-type primases, OLD family nucleases and RecR proteins. Aravind L, Leipe DD, Koonin EV;. Nucleic Acids Res 1998;26:4205-4213. [2]. 9224947. Cloning and analysis of the dnaG gene encoding Pseudomonas putida DNA primase. Szafranski P, Smith CL, Cantor CR;. Biochim Biophys Acta 1997;1352:243-248. [3]. 8294018. The Haemophilus influenzae dnaG sequence and conserved bacterial primase motifs. Versalovic J, Lupski JR;. Gene 1993;136:281-286. [4]. 9121560. An atypical topoisomerase II from Archaea with implications for meiotic recombination. Bergerat A, de Massy B, Gadelle D, Varoutas PC, Nicolas A, Forterre P;. Nature 1997;386:414-417. (from Pfam)

Date:

2024-10-16

Date:

2021-08-24

This model describes topoisomerase III from bacteria and its equivalents encoded on plasmids. The gene is designated topB if found in the bacterial chromosome, traE on conjugative plasmid RP4, etc. These enzymes are involved in the control of DNA topology. DNA topoisomerase III belongs to the type I topoisomerases, which are ATP-independent.

Gene:

topB

Date:

2021-04-27