Document Detail

Mutations in domain III alpha of the Mu transposase: evidence suggesting an active site component which interacts with the Mu-host junction.
MedLine Citation:
PMID:  9735286     Owner:  NLM     Status:  MEDLINE    
A series of point mutations was constructed in domain IIIalpha of the Mu A protein. The mutant transposases were purified and assayed for their ability to promote various aspects of the in vitro Mu DNA strand transfer reaction. All mutants with discernable phenotypes were inhibited in stable synapsis (Type 0 or Type 1 complex formation). In contrast, these mutant proteins were capable of LER formation (a transient early reaction intermediate in which the Mu left and right ends have been synapsed with the enhancer), at levels comparable to wild-type transposase. These proteins therefore comprise a novel class of transposase mutants, which are specifically inhibited in stable transpososome assembly. The defect in these proteins was also uniformly suppressed by either Mn2+, or the Mu B protein in the presence of ATP and target DNA. Striking phenotypic similarities were recognized between the domain IIIalpha transposase mutant characteristics noted above, and those for substrate mutants carrying a terminal base-pair substitution at the point of cleavage on the donor molecule. This phenotypic congruence suggests that the alterations in either protein or DNA are exerting an effect on the same step of the reaction i.e., engagement of the terminal nucleotide by the active site. We suggest that domain IIIalpha of the transposase comprises the substrate binding pocket of the active site which interacts with the Mu-host junction.
D Z Naigamwalla; C J Coros; Z Wu; G Chaconas
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of molecular biology     Volume:  282     ISSN:  0022-2836     ISO Abbreviation:  J. Mol. Biol.     Publication Date:  1998 Sep 
Date Detail:
Created Date:  1998-10-14     Completed Date:  1998-10-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985088R     Medline TA:  J Mol Biol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  265-74     Citation Subset:  IM    
Copyright Information:
Copyright 1998 Academic Press.
Department of Biochemistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada.
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MeSH Terms
Amino Acid Sequence
Bacteriophage mu / enzymology,  genetics*
Binding Sites / genetics
DNA, Bacterial / metabolism
DNA, Viral / metabolism
Molecular Sequence Data
Point Mutation / genetics*
Protein Processing, Post-Translational / genetics
Protein Structure, Tertiary
Transposases / chemistry,  genetics*,  metabolism
Viral Proteins / chemistry,  genetics,  metabolism
Reg. No./Substance:
0/DNA, Bacterial; 0/DNA, Viral; 0/Viral Proteins; EC 2.7.-/mu transposase; EC 2.7.7.-/Transposases

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