由重组α-中间丝蛋白组装中间丝的途径。

The pathway of assembly of intermediate filaments from recombinant alpha-internexin.

作者信息

Abumuhor I A, Spencer P H, Cohlberg J A

机构信息

Department of Chemistry and Biochemistry, California State University, Long Beach, California, 90840, USA.

出版信息

J Struct Biol. 1998 Nov;123(3):187-98. doi: 10.1006/jsbi.1998.4040.

DOI:10.1006/jsbi.1998.4040

PMID:9878574

Abstract

The pathway of filament assembly from the neuronal intermediate filament alpha-intermexin was investigated. Optimal assembly occurred in solutions of pH 6.5 to 7 and moderate ionic strength at 37 degrees C. Short filaments formed upon dialysis at 24 degrees C, which elongated further when incubated at 37 degrees C. Soluble forms of alpha-internexin were characterized by analytical ultracentrifugation and electron microscopy. In 10 mM Tris, pH 8, conditions that favor formation of tetramers and other small oligomers for other intermediate filament proteins, alpha-internexin formed 10.5 S particles, apparently unit-length half-filaments in the form of rods 10.6 nm in diameter and 68 nm long. Dialysis vs the same buffer with added 10 mM NaCl yielded 16 S rods, probably unit-length filaments, of the same length but 13.0 nm in diameter. At 50 mM NaCl, rods about 13 nm in diameter and heterogeneous in length were observed in electron micrographs, apparently formed from longitudinal annealing of unit-length rods. The results favor a model of assembly in which coiled coil dimers aggregate laterally to form first "unit-length half-filaments" (Herrmann, H., and Aebi, U. (1998) Curr. Opin. Struct. Biol. 8, 177-185) and then "unit-length filaments," which subsequently elongate by annealing.

摘要

研究了源自神经元中间丝α-中间丝蛋白的丝状体组装途径。在pH 6.5至7的溶液以及37℃的中等离子强度下发生最佳组装。在24℃透析时形成短丝，当在37℃孵育时进一步伸长。通过分析超速离心和电子显微镜对α-中间丝蛋白的可溶形式进行了表征。在10 mM Tris，pH 8的条件下，有利于其他中间丝蛋白形成四聚体和其他小寡聚体，α-中间丝蛋白形成10.5 S颗粒，显然是单位长度的半丝，呈直径10.6 nm、长68 nm的杆状。与添加了10 mM NaCl的相同缓冲液进行透析，得到16 S杆状结构，可能是单位长度的丝，长度相同但直径为13.0 nm。在50 mM NaCl时，在电子显微镜照片中观察到直径约13 nm且长度不均一的杆状结构，显然是由单位长度杆状结构的纵向退火形成的。结果支持一种组装模型，即卷曲螺旋二聚体横向聚集首先形成“单位长度半丝”（赫尔曼，H.，和埃比，U.（1998年）《当代结构生物学观点》8，177 - 185），然后形成“单位长度丝”，随后通过退火伸长。