RRC ID 3194
著者 Mori H, Shimizu Y, Ito K.
タイトル Superactive SecY variants that fulfill the essential translocation function with a reduced cellular quantity.
ジャーナル J Biol Chem
Abstract The fifth and the sixth cytoplasmic regions (C5 and C6) of SecY are important for the SecA-driven preprotein translocation reaction. A cold-sensitive mutation, secY205 (Tyr-429 --> Asp), in C6 impairs the ATP- and precursor-dependent SecA insertion into the membrane. We now identified second site mutations that suppressed the defect. Cis-placement of these mutations proved to suppress mutations at another essential residue (Arg-357) of SecY as well. Thus, they tolerate the otherwise defective SecY alterations in the same molecule. Two alterations (Ile-195 to Ser in TM5 region and Ile-408 to Leu in TM10 region) were found to make the translocation channel more active, because it enabled cells to survive with reduced content of the SecYE complex. These mutations only very weakly suppressed a signal sequence defect of the lambda receptor protein. The mutant SecYEG translocase exhibited higher than normal activity in vitro, being accompanied by striking independence of the proton motive force as well as by stabilization of a bound and active SecA species against urea treatment. These results have been interpreted in terms of balance shifts between channel closing and channel opening alterations in the SecYEG translocase.
巻・号 277(50)
ページ 48550-7
公開日 2002-12-13
DOI 10.1074/jbc.M204436200
PII S0021-9258(19)33090-X
PMID 12351621
MeSH Amino Acid Sequence Escherichia coli / metabolism Escherichia coli Proteins / chemistry Escherichia coli Proteins / genetics Escherichia coli Proteins / metabolism Escherichia coli Proteins / physiology* Genes, Suppressor Molecular Sequence Data Mutation Protein Transport SEC Translocation Channels
IF 4.238
引用数 8
WOS 分野 BIOCHEMISTRY & MOLECULAR BIOLOGY
リソース情報
原核生物(大腸菌) CV-49(MC4100)?