caa a22 4500 397556128 CHVBK 20180308164802.0 cr unu---uuuuu 161202e199606 xx s 000 0 eng 10.1093/oxfordjournals.jbchem.a021358 doi (NATIONALLICENCE)oxford-10.1093/oxfordjournals.jbchem.a021358 Roles of the Conserved Cytoplasmic Region and Non-Conserved Carboxy-Terminal Region of SecE in Escherichia coli Protein Translocase [Elektronische Daten] [Vesa P. Kontinen, Miyuki Yamanaka, Ken-ichi Nishiyama, Hajime Tokuda] SecE, an essential membrane component of the Escherichia coli protein translocase, consists of 127 ami no acid residues. Only a part of the second putative cytoplasmic region comprising some 13 residues is essential for the SecE function as long as the proper topological arrangement is retained. The Trp84 and Pro85 residues of this region are conserved in all eubacterial SecE homologues. The conservation of positively charged residues corresponding to ArgSO and Lys81 is also substantial. We deleted or replaced these residues to assess their roles in the SecE function. Deletion of the Arg80-Lys81 dipeptide did not abolish the SecE function whereas that of Trp84 or Pro85 caused a loss of the function. Strikingly, however, replacement of Pro85 with either Gly, Ser, or Ala, and that of Trp84 with Lys did not abolish the SecE function. These results indicate that the strong conservation of these residues does not reflect their obligatory requirement for the SecE function. A chimeric SecE possessing the cytoplasmic region of the E. coli SecE and the following region of the Bacillus subtilis SecE was able to form the translocation machinery together with SecA, SecY, and SecG. Although a Leu to Arg mutation at position 108 has been thought to cause a loss of signal recognition fidelity and thereby suppress a signal sequence defect, the same mutation at position 111 caused a complete loss of the function. The levels of SecY and SecG in the secEcsE501 mutant, which expresses SecE at a decreased level and is sensitive to low temperature, increased upon the expression of functional SecE derivatives, irrespective of the site of mutation, suggesting that the levels of SecY and SecG are co-operatively determined by the level of functional, but not non-functional, SecE. Based on these results, the SecE function in the translocase is discussed. © by the Journal of Biochemistry Regular Papers nationallicence conserved residues nationallicence Escherichia coli nationallicence protein translocation nationallicence SecE nationallicence SecY nationallicence Kontinen Vesa P. Institute of Molecular and Celllular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113 aut Yamanaka Miyuki Institute of Molecular and Celllular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113 aut Nishiyama Ken-ichi Institute of Molecular and Celllular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113 aut Tokuda Hajime Institute of Molecular and Celllular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113 aut The Journal of Biochemistry Oxford University Press 119/6(1996-06), 1124-1130 0021-924X 119:6<1124 1996 119 jbchem https://doi.org/10.1093/oxfordjournals.jbchem.a021358 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/oxfordjournals.jbchem.a021358 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kontinen Vesa P. Institute of Molecular and Celllular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113 aut NATIONALLICENCE 700 1- Yamanaka Miyuki Institute of Molecular and Celllular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113 aut NATIONALLICENCE 700 1- Nishiyama Ken-ichi Institute of Molecular and Celllular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113 aut NATIONALLICENCE 700 1- Tokuda Hajime Institute of Molecular and Celllular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113 aut NATIONALLICENCE 773 0- The Journal of Biochemistry Oxford University Press 119/6(1996-06), 1124-1130 0021-924X 119:6<1124 1996 119 jbchem Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford