Structure, crystal packing and molecular dynamics of the calponin-homology domain of Schizosaccharomyces pombe Rng2.
Schizosaccharomyces pombe Rng2 is an IQGAP protein that is essential for the assembly of an actomyosin ring during cytokinesis. Rng2 contains an amino-terminal calponin-homology (CH) domain, 11 IQ repeats and a RasGAP-homology domain. CH domains are known mainly for their ability to bind F-actin, although they have other ligands in vivo and there are only few examples of actin-binding single CH domains. The structures of several CH domains have already been reported, but this is only the third report of an actin-binding protein that contains a single CH domain (the structures of calponin and EB1 have been reported previously). The 2.21 A resolution crystal structure of the amino-terminal 190 residues of Rng2 from Br- and Hg-derivatives includes 40 residues (150-190) carboxyl-terminal to the CH domain that resemble neither the extended conformation seen in utrophin, nor the compact conformation seen in fimbrin, although residues 154-160 form an unstructured coil which adopts a substructure similar to dystrophin residues 240-246 in the carboxyl-terminal portion of the CH2 domain. This region wraps around the stretch of residues that would be equivalent to the proposed actin-binding site ABS1 and ABS2 from dystrophin. This distinctive feature is absent from previously published CH-domain structures. Another feature revealed by comparing the two derivatives is the presence of two loop conformations between Tyr92 and Arg99.
Institute of Molecular and Cell Biology, 61 Biopolis Drive (Proteos), Singapore 138673, Singapore. chernhoe@imcb.a-star.edu.sg
Chern-Hoe
CH
Wang
Mohan K
MK
Balasubramanian
Terje
T
Dokland
D001665:Binding Sites; D001966:Bromine / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000737:chemistry*; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D020690:GTPase-Activating Proteins / Q000737:chemistry* / Q000378:metabolism*; D008628:Mercury / Q000494:pharmacology; D008840:Microfilament Proteins; D008958:Models, Molecular; D011487:Protein Conformation; D012568:Schizosaccharomyces / Q000737:chemistry*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D000096985:Calponins
D001966:Bromine; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D020690:GTPase-Activating Proteins; D008628:Mercury; D008840:Microfilament Proteins; D029702:Schizosaccharomyces pombe Proteins; D000096985:Calponins; C114172:Rng2 protein, S pombe