The Mycoplasma genitalium MG352-encoded protein is a Holliday junction resolvase that has a non-functional orthologue in Mycoplasma pneumoniae.
Recombination between repeated DNA elements in the genomes of Mycoplasma species appears to lie at the basis of antigenic variation of several essential surface proteins. It is therefore imperative that the DNA recombinatorial pathways in mycoplasmas be unravelled. Here, we describe the proteins encoded by the Mycoplasma genitalium MG352 and Mycoplasma pneumoniae MPN528a genes (RecU(Mge) and RecU(Mpn) respectively), which share sequence similarity with RecU Holliday junction (HJ) resolvases. RecU(Mge) was found to: (i) bind HJ substrates and large double-stranded DNA molecules and (ii) cleave HJ substrates at the sequence 5'-(G) /(T) C↓(C) /(T) T(A) /(G) G-3' in the presence of Mn(2+). Interestingly, RecU(Mpn) (from M. pneumoniae subtype 2 strains) did not possess obvious DNA binding or cleavage activities, which was found to be caused by the presence of a glutamic acid residue at position 67 of the protein, which is not conserved in RecU(Mge). Additionally, RecU(Mpn) appears not to be expressed by subtype 1 M. pneumoniae strains, as these possess a TAA translation termination codon at position 181-183 of MPN528a. We conclude that RecU(Mge) is a HJ resolvase that may play a central role in recombination in M. genitalium.
Sluijter
Marcel
M
Erasmus MC-Sophia Children's Hospital, Laboratory of Pediatrics, Pediatric Infectious Diseases and Immunity, PO Box 2040, 3000 CA Rotterdam, the Netherlands.
Kaptein
Edwin
E
Spuesens
Emiel B M
EB
Hoogenboezem
Theo
T
Hartwig
Nico G
NG
Van Rossum
Annemarie M C
AM
Vink
Cornelis
C
D001483:Base Sequence; D003067:Coenzymes / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism; D045565:Holliday Junction Resolvases / Q000235:genetics* / Q000378:metabolism*; D008345:Manganese / Q000378:metabolism; D008969:Molecular Sequence Data; D045704:Mycoplasma genitalium / Q000201:enzymology* / Q000235:genetics*; D009177:Mycoplasma pneumoniae / Q000201:enzymology* / Q000235:genetics*; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid
D003067:Coenzymes; D004269:DNA, Bacterial; D008345:Manganese; D045565:Holliday Junction Resolvases