Dissection of a Human Septin: Definition and Characterization of Distinct Domains within Human SEPT4
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- 作者：Wanius Garcia ; Ana Paula Ulian de Araú ; jo ; Mario de Oliveira Neto ; Michel R. M. Ballestero ; Igor Polikarpov ; Manami Tanaka ; Tomoo Tanaka ; Richard Charles Garratt
- 刊名：Biochemistry
- 出版年：2006
- 出版时间：November 21, 2006
- 年：2006
- 卷：45
- 期：46
- 页码：13918 - 13931
- 全文大小：678K
- 年卷期：v.45,no.46(November 21, 2006)
- ISSN：1520-4995
文摘
The septins are a conserved family of guanosine-5'-triphosphate (GTP)-binding proteins. Inmammals they are involved in a variety of cellular processes, such as cytokinesis, exocytosis, and vesicletrafficking. Specifically, SEPT4 has also been shown to be expressed in both human colorectal cancerand malignant melanoma, as well as being involved in neurodegenerative disorders. However, many ofthe details of the modes of action of septins in general remain unclear, and little is known of their detailedmolecular architecture. Here, we define explicitly and characterize the domains of human SEPT4. Regionscorresponding to the N-terminal, GTPase, and C-terminal domains as well as the latter two together weresuccessfully expressed in Escherichia coli in soluble form and purified by affinity and size-exclusionchromatographies. The purified domains were analyzed by circular dichroism spectroscopy, fluorescencespectroscopy, dynamic light scattering, and small-angle X-ray scattering, as well as with bioinformaticstools. Of the three major domains that comprise SEPT4, the N-terminal domain contains little regularsecondary structure and may be intrinsically unstructured. The central GTPase domain is a mixed 
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structure, probably based on an open sheet. As defined here, it is catalytically active and forms stablehomodimers in vitro. The C-terminal domain also forms homodimers and can be divided into two regions,the second of which is -helical and consistent with a coiled-coil structure. These studies should providea useful basis for future biophysical studies of SEPT4, including the structural basis for their involvementin diseases such as cancer and neurodegenerative disorders.
/structure, probably based on an open sheet. As defined here, it is catalytically active and forms stablehomodimers in vitro. The C-terminal domain also forms homodimers and can be divided into two regions,the second of which is -helical and consistent with a coiled-coil structure. These studies should providea useful basis for future biophysical studies of SEPT4, including the structural basis for their involvementin diseases such as cancer and neurodegenerative disorders.