Dissecting functional similarities of ribosome-associated chaperones from Saccharomyces cerevisiae and Escherichia coli.
Ribosome-tethered chaperones that interact with nascent polypeptide chains have been identified in both prokaryotic and eukaryotic systems. However, these ribosome-associated chaperones share no sequence similarity: bacterial trigger factors (TF) form an independent protein family while the yeast machinery is Hsp70-based. The absence of any component of the yeast machinery results in slow growth at low temperatures and sensitivity to aminoglycoside protein synthesis inhibitors. After establishing that yeast ribosomal protein Rpl25 is able to recruit TF to ribosomes when expressed in place of its Escherichia coli homologue L23, the ribosomal TF tether, we tested whether such divergent ribosome-associated chaperones are functionally interchangeable. E. coli TF was expressed in yeast cells that lacked the endogenous ribosome-bound machinery. TF associated with yeast ribosomes, cross-linked to yeast nascent polypeptides and partially complemented the aminoglycoside sensitivity, demonstrating that ribosome-associated chaperones from divergent organisms share common functions, despite their lack of sequence similarity.
Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany.
Thomas
T
Rauch
Heather A
HA
Hundley
Chris
C
Pfund
Renee D
RD
Wegrzyn
William
W
Walter
Günter
G
Kramer
So-Young
SY
Kim
Elizabeth A
EA
Craig
Elke
E
Deuerling
D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D019143:Evolution, Molecular; D005816:Genetic Complementation Test; D018840:HSP70 Heat-Shock Proteins / Q000502:physiology; D018832:Molecular Chaperones / Q000378:metabolism / Q000502:physiology*; D008969:Molecular Sequence Data; D019696:Peptidylprolyl Isomerase / Q000378:metabolism / Q000502:physiology; D017510:Protein Folding; D011499:Protein Processing, Post-Translational; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D012270:Ribosomes / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism / Q000502:physiology
D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; C043816:ribosomal protein L23, E coli; C031127:ribosomal protein L25; C403324:trigger factor, E coli; D019696:Peptidylprolyl Isomerase