The spindle matrix protein, Chromator, is a novel tubulin binding protein that can interact with both microtubules and free tubulin

• Published in: PloS one Vol. 9; no. 7; p. e103855
• Main Authors: Yao, Changfu, Wang, Chao, Li, Yeran, Ding, Yun, Rath, Uttama, Sengupta, Saheli, Girton, Jack, Johansen, Kristen M, Johansen, Jørgen
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 29-07-2014; Public Library of Science (PLoS)
• Subjects: Amino acids; Animals; Animals, Genetically Modified - metabolism; Antibodies - immunology; Biochemistry; Biology and Life Sciences; Biophysics; Cell cycle; Cell division; Chemical properties; Chromosomes; Drosophila; Drosophila melanogaster - metabolism; Drosophila Proteins - chemistry; Drosophila Proteins - immunology; Drosophila Proteins - metabolism; Experiments; Immunoprecipitation; Insects; Kinases; Laboratories; Localization; Matrix protein; Microtubules; Microtubules - chemistry; Microtubules - metabolism; Mitosis; Molecular biology; Nuclear Matrix-Associated Proteins - chemistry; Nuclear Matrix-Associated Proteins - immunology; Nuclear Matrix-Associated Proteins - metabolism; Phase transitions; Protein Binding; Protein Structure, Tertiary; Proteins; RNA-mediated interference; Spindles; Tubulin; Tubulin - chemistry; Tubulin - immunology; Tubulin - metabolism; United States > US; Iowa
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0103855

The chromodomain protein, Chromator, is localized to chromosomes during interphase; however, during cell division together with other nuclear proteins Chromator redistributes to form a macro molecular spindle matrix complex that embeds the microtubule spindle apparatus. It has been demonstrated that the CTD of Chromator is sufficient for localization to the spindle matrix and that expression of this domain alone could partially rescue Chro mutant microtubule spindle defects. Furthermore, the presence of frayed and unstable microtubule spindles during mitosis after Chromator RNAi depletion in S2 cells indicated that Chromator may interact with microtubules. In this study using a variety of biochemical assays we have tested this hypothesis and show that Chromator not only has binding activity to microtubules with a Kd of 0.23 µM but also to free tubulin. Furthermore, we have mapped the interaction with microtubules to a relatively small stretch of 139 amino acids in the carboxy-terminal region of Chromator. This sequence is likely to contain a novel microtubule binding interface since database searches did not find any sequence matches with known microtubule binding motifs.