Mutations at Pro67 in the RecA protein P-loop motif differentially modify coprotease function and separate coprotease from recombination activities
UMass Chan Affiliations
Department of Biochemistry and Molecular BiologyDocument Type
Journal ArticlePublication Date
1995-04-14Keywords
Amino Acid SequenceBacterial Proteins
Endopeptidases
Hydrolysis
Molecular Sequence Data
Mutation
Nucleic Acids
Proline
Rec A Recombinases
*Recombination, Genetic
Repressor Proteins
*Serine Endopeptidases
Life Sciences
Medicine and Health Sciences
Metadata
Show full item recordAbstract
The functional significance of residues in the RecA protein P-loop motif was assessed by analyzing 100 unique mutants with single amino acid substitutions in this region. Comparison of the effects on the LexA coprotease and recombination activities shows that Pro67 is unique among these residues because only at this position did we find substitutions that caused differential effects on these functions. One mutant, Pro67-->Trp, displays high constitutive coprotease activity and a moderate inhibitory effect on recombination functions. Glu and Asp substitutions result in low level constitutive coprotease activity but dramatically reduce recombination activity. The purified Pro67-->Trp protein shows a completely relaxed specificity for NTP cofactors in LexA cleavage assays and can use shorter length oligonucleotides as cofactors for cleavage of lambda cI repressor than can wild type RecA. Interestingly, both the mutant protein and wild type RecA can use very short oligonucleotides, e.g. (dA)6 and (dT)6, as cofactors for LexA cleavage. We have also found two mutations at position 67, which are completely defective for LexA coprotease activity in vivo but still maintain recombinational DNA repair (Pro67-->Lys) and homologous recombination (Pro67-->Lys and Pro67-->Arg) activities. These findings show that the recombination activities of RecA are mutationally separable from the coprotease function and that Pro67 is located in a functionally important position in the RecA structure.Source
J Biol Chem. 1995 Apr 14;270(15):8411-9.
DOI
10.1074/jbc.270.15.8411Permanent Link to this Item
http://hdl.handle.net/20.500.14038/42465PubMed ID
7721735Related Resources
ae974a485f413a2113503eed53cd6c53
10.1074/jbc.270.15.8411