Hydrophobic carboxy-terminal residues dramatically reduce protein levels in the haloarchaeon Haloferax volcanii.
Proteolysis is important not only to cell physiology but also to the successful development of biocatalysts. While a wide-variety of signals are known to trigger protein degradation in bacteria and eukaryotes, these mechanisms are poorly understood in archaea, known for their ability to withstand harsh conditions. Here we present a systematic study in which single C-terminal amino acid residues were added to a reporter protein and shown to influence its levels in an archaeal cell. All 20 amino acid residues were examined for their impact on protein levels, using the reporter protein soluble modified red-shifted GFP (smRS-GFP) expressed in the haloarchaeon Haloferax volcanii as a model system. Addition of hydrophobic residues, including Leu, Cys, Met, Phe, Ala, Tyr, Ile and Val, gave the most pronounced reduction in smRS-GFP levels compared with the addition of either neutral or charged hydrophilic residues. In contrast to the altered protein levels, the C-terminal alterations had no influence on smRS-GFP-specific transcript levels, thus revealing that the effect is post-transcriptional.
University of Florida, Department of Microbiology and Cell Science, Gainesville, FL 32611-0700, USA.
Christopher J
CJ
Reuter
University of Florida, Department of Microbiology and Cell Science, Gainesville, FL 32611-0700, USA.
Sivakumar
S
Uthandi
University of Florida, Department of Microbiology and Cell Science, Gainesville, FL 32611-0700, USA.
Jose A
JA
Puentes
University of Florida, Department of Microbiology and Cell Science, Gainesville, FL 32611-0700, USA.
Julie A
JA
Maupin-Furlow
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism*; D019843:Archaeal Proteins / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D019622:Haloferax volcanii / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D019642:RNA, Archaeal / Q000378:metabolism
D000596:Amino Acids; D019843:Archaeal Proteins; D019642:RNA, Archaeal; D049452:Green Fluorescent Proteins