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Differential affinity and cooperativity functions of the amino-terminal 70 residues of lambda integrase.

DIR@IMTECH: CSIR-Institute of Microbial Technology

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Title Differential affinity and cooperativity functions of the amino-terminal 70 residues of lambda integrase.
 
Creator Sarkar, Dibyendu
Azaro, Marco A
Aihara, Hideki
Papagiannis, Christie V
Tirumalai, Radhakrishna
Nunes-Düby, Simone E
Johnson, Reid C
Ellenberger, Tom
Landy, Arthur
 
Subject QR Microbiology
 
Description The site-specific recombinase (Int) of bacteriophage lambda is a heterobivalent DNA-binding protein that binds two different classes of DNA-binding sites within its recombination target sites. The several functions of Int are apportioned between a large carboxy-terminal domain that cleaves and ligates DNA at each of its four "core-type" DNA-binding sites and a small amino-terminal domain, whose primary function is binding to each of its five "arm-type" DNA sites, which are distant from the core region. Int bridges between the two classes of binding sites are facilitated by accessory DNA-bending proteins that along with Int comprise higher-order recombinogenic complexes. We show here that although the 64 amino-terminal residues of Int bind efficiently to a single arm site, this protein cannot form doubly bound complexes on adjacent arm sites. However, 1-70 Int does show the same cooperative binding to adjacent arm sites as the full length protein. We also found that 1-70 Int specifies cooperative interactions with the accessory protein Xis when the two are bound to their adjacent cognate sites P2 and X1, respectively. To complement the finding that these two amino-terminal domain functions (along with arm DNA binding) are all specified by residues 1-70, we determined that Thr75 is the first residue of the minimal carboxy-terminal domain, thereby identifying a specific interdomain linker region. We have measured the affinity constants for Int binding to each of the five arm sites and the cooperativity factors for Int binding to the two pairs of adjacent arm sites, and we have identified several DNA structural features that contribute to the observed patterns of Int binding to arm sites. Taken together, the results highlight several interesting features of arm DNA binding that invite speculation about additional levels of complexity in the regulation of lambda site-specific recombination.
 
Publisher Elsevier Science
 
Date 2002-12-06
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://crdd.osdd.net/open/888/1/sarkar2002.pdf
Sarkar, Dibyendu and Azaro, Marco A and Aihara, Hideki and Papagiannis, Christie V and Tirumalai, Radhakrishna and Nunes-Düby, Simone E and Johnson, Reid C and Ellenberger, Tom and Landy, Arthur (2002) Differential affinity and cooperativity functions of the amino-terminal 70 residues of lambda integrase. Journal of molecular biology, 324 (4). pp. 775-89. ISSN 0022-2836
 
Relation http://www.sciencedirect.com/science/article/pii/S0022283602011993
http://crdd.osdd.net/open/888/