TY - JOUR
T1 - Post-translational modification of the S-layer glycoprotein occurs following translocation across the plasma membrane of the haloarchaeon Haloferax volcanii
AU - Eichler, Jerry
PY - 2001/9/27
Y1 - 2001/9/27
N2 - The halophilic archaeon Haloferax volcanii is surrounded by a protein shell solely comprised of the S-layer glycoprotein. While the gene sequence and glycosylation pattern of the protein and indeed the three-dimensional structure of the surface layer formed by the protein have been described, little is known of the biosynthesis of the S-layer glycoprotein. In the following, pulse-chase radiolabeling and cell-fractionation studies were employed to reveal that newly synthesized S-layer glycoprotein undergoes a maturation step following translocation of the protein across the plasma membrane. The processing step, detected as an increase in the apparent molecular mass of the S-layer glycoprotein, is unaffected by inhibition of protein synthesis and is apparently unrelated to glycosylation of the protein. Maturation requires the presence of magnesium ions, involved in membrane association of the S-layer glycoprotein, and results in increased hydrophobicity of the protein as revealed by enhanced detergent binding. Thus, along with protein glycosylation, additional post-translational modifications apparently occur on the external face of the haloarchaeal plasma membrane, the proposed topological homologue of the lumenal face of the eukaryal endoplasmic reticulum membrane.
AB - The halophilic archaeon Haloferax volcanii is surrounded by a protein shell solely comprised of the S-layer glycoprotein. While the gene sequence and glycosylation pattern of the protein and indeed the three-dimensional structure of the surface layer formed by the protein have been described, little is known of the biosynthesis of the S-layer glycoprotein. In the following, pulse-chase radiolabeling and cell-fractionation studies were employed to reveal that newly synthesized S-layer glycoprotein undergoes a maturation step following translocation of the protein across the plasma membrane. The processing step, detected as an increase in the apparent molecular mass of the S-layer glycoprotein, is unaffected by inhibition of protein synthesis and is apparently unrelated to glycosylation of the protein. Maturation requires the presence of magnesium ions, involved in membrane association of the S-layer glycoprotein, and results in increased hydrophobicity of the protein as revealed by enhanced detergent binding. Thus, along with protein glycosylation, additional post-translational modifications apparently occur on the external face of the haloarchaeal plasma membrane, the proposed topological homologue of the lumenal face of the eukaryal endoplasmic reticulum membrane.
KW - Archaea
KW - Haloferax volcanii
KW - Membrane protein
KW - Plasma membrane
KW - Post-translational modification
UR - http://www.scopus.com/inward/record.url?scp=0034832009&partnerID=8YFLogxK
U2 - 10.1046/j.1432-1327.2001.02361.x
DO - 10.1046/j.1432-1327.2001.02361.x
M3 - Article
AN - SCOPUS:0034832009
SN - 0014-2956
VL - 268
SP - 4366
EP - 4373
JO - European Journal of Biochemistry
JF - European Journal of Biochemistry
IS - 15
ER -