TraA
Encyclopedia
The traA gene codes for relaxase
, which is an enzyme that initiates plasmid DNA transfer during bacterial conjugation
. Relaxase forms a relaxosome
complex with auxiliary proteins to initiate conjugation. Relaxosome binds to the origin of transfer
(oriT) sequence and cleaves the DNA strand that will be transferred (the T strand).
The TraA gene is usually found on megaplasmids in bacteria, and it is somewhat conserved among different bacterial species. Thirty-one percent and 29 percent of Rhodococcus erthypolis TraA residues are identical to Gordonia westfalica TraA and Arthrobacter aurescens TraA, respectively (Yang et al. 2006).
Among actinomycetales
, it is common to find that the traA gene codes for both relaxase and helicase
.
Relaxase
A relaxase is a single-strand DNA transesterase enzyme produced by some prokaryotes and viruses. Relaxases are responsible for site- and strand-specific nicks in double-stranded DNA. Known relaxases belong to the Rolling Circle Replication initiator superfamily of enzymes and fall into two broad...
, which is an enzyme that initiates plasmid DNA transfer during bacterial conjugation
Bacterial conjugation
Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells...
. Relaxase forms a relaxosome
Relaxosome
Relaxosome is the complex of proteins that facilitates plasmids during bacterial conjugation. The proteins are encoded by the tra gene in the origin of transfer, oriT, region. The most important of these proteins is relaxase, which is responsible for beginning the conjugation process by cutting...
complex with auxiliary proteins to initiate conjugation. Relaxosome binds to the origin of transfer
Origin of transfer
An origin of transfer is a short sequence of DNA that is necessary for transfer of a bacterial plasmid from a bacterial host to recipient during bacterial conjugation. The oriT is cis-acting - it is found on the same plasmid that is being transferred, and is transferred along with the plasmid...
(oriT) sequence and cleaves the DNA strand that will be transferred (the T strand).
The TraA gene is usually found on megaplasmids in bacteria, and it is somewhat conserved among different bacterial species. Thirty-one percent and 29 percent of Rhodococcus erthypolis TraA residues are identical to Gordonia westfalica TraA and Arthrobacter aurescens TraA, respectively (Yang et al. 2006).
Among actinomycetales
Actinomycetales
Actinomycetales is an order of Actinobacteria. They are very diverse and contain a variety of subdivisions as well as yet unclassified isolates. This is mainly because some genera are very difficult to classify because of a highly niche-dependent phenotype...
, it is common to find that the traA gene codes for both relaxase and helicase
Helicase
Helicases are a class of enzymes vital to all living organisms. They are motor proteins that move directionally along a nucleic acid phosphodiester backbone, separating two annealed nucleic acid strands using energy derived from ATP hydrolysis.-Function:Many cellular processes Helicases are a...
.