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.
Wang
Chern-Hoe
CH
Institute of Molecular and Cell Biology, 61 Biopolis Drive (Proteos), Singapore 138673, Singapore. chernhoe@imcb.a-star.edu.sg
Balasubramanian
Mohan K
MK
Dokland
Terje
T
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