Characterization of MobK nuclease protein

12 10 2022

Welcome everyone to new academic year. We are restarting our seminars and you are invited next Monday, 17th of October at 2 pm. This year we are happy it invite you to 102B seminar room. First seminar entitled “The fascinating world of DNA breaking-rejoining enzymes: characterization of MobK DNA_BRE_C nuclease protein” will be delivered by dr. Paweł Wawrzyniak from the Department of Bacterial Genetics.

Abstract:

DNA breaking-rejoining activity was described for different types of nucleases: DNA_BRE_Cs, DDE and serine recombinases, and rolling circle replication (RCR) initiators (e.g. HUH, Rep_trans nucleases). They differ from each other. But in general, they share a “simply clever” mechanism for subsequent DNA cleavage and religation. These two reactions take place without external energy sources and (predominantly) without accessory proteins. DNA breaking-rejoining nucleases have a remarkable potential for initiating various types of processes critical for eukaryotic, archeal, and prokaryotic chromosomes as well as mobile genetic elements.

Nucleases containing DNA breaking-rejoining C-terminal domain (DNA_BRE_C) are one of the most significant and widely distributed groups of enzymes involved in DNA modification. DNA_BRE_C superfamily includes e.g. tyrosine recombinases (YRs). Due to their use in molecular biology different YRs (e.g. Cre, λ Int, Flp XerC/D) have been characterized in detail. We have noticed that intensive research on YRs enzymes does not include a potentially important group of these proteins. Searching sequence databases, we identified about 10000 putative atypical YR-like proteins encoded mainly by bacterial plasmids, with an “orphan” catalytic domain (typical YRs are composed of C- terminal catalytic domain and ~ 100 aa α-helical N- terminal Core DNA Binding domain). We named them “small” DNA_BRE_Cs. What is more, in our lab, we indicated for the first time, that “small” DNA_BRE_Cs can perform a new biological role (not reported for DNA_BRE_Cs) – mobilization (Mob) for DNA transfer from donor to recipient bacterial cell via type four secretion system in the conjugation process. Recently published results of our work concerning the “small” DNA_BRE_C protein MobK from pIGRK plasmid proved that is a convenient research model for in vivo and in vitro testing and revealed additional interesting features of this protein.