title: Characterization of ClpS2, an essential adaptor protein for the cyanobacterium Synechococcus elongatus.
abstract: The adaptor protein ClpS associates to the Clp protease and promotes degradation of N-end rule substrates in eubacteria and in algal/plant chloroplasts. Cyanobacteria are unusual in having two distinct ClpS paralogs. Although ClpSl is typical of bacterial ClpS, ClpS2 differs in crucial ways. ClpS2 in Synechococcus elongatus is a relatively low-abundant, soluble protein essential for phototrophic growth. Like ClpSl, ClpS2 binds to the ClpCP3/R protease to block α-casein degradation and promote that of N-end rule substrates in vitro. However, their substrate specificity differs, with ClpSl recognizing destabilizing Phe and Tyr residues at the substrate N-terminus whereas ClpS2 recognizes Leu. Overall, ClpS2 appears to have independently evolved in cyanobacteria to degrade a particular group of proteins, whose turnover is vital for cell viability.
authors.affiliation: Department of Biological and Environmental Sciences, Gothenburg University, Box 461, 405 30 Gothenburg, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Tryggvesson
authors.affiliation: Department of Biological and Environmental Sciences, Gothenburg University, Box 461, 405 30 Gothenburg, Sweden.
authors.forename: Frida M
authors.initials: FM
authors.lastname: Ståhlberg
authors.affiliation: Department of Biological and Environmental Sciences, Gothenburg University, Box 461, 405 30 Gothenburg, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Töpel
authors.affiliation: Department of Applied Biosciences, Kinki University, Nakamachi 3327-204, Nara, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Tanabe
authors.affiliation: Zentrum fur Molekulare Biologie der Universitat Heidelberg, Im Neuenheimre Feld 282, D-69120 Heidelberg, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Mogk
authors.affiliation: Department of Biological and Environmental Sciences, Gothenburg University, Box 461, 405 30 Gothenburg, Sweden. Electronic address: adrian.clarke@bioenv.gu.se.
authors.forename: Adrian K
authors.initials: AK
authors.lastname: Clarke
mesh_terms: D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017124:Conserved Sequence; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D050296:Microbial Viability; D008969:Molecular Sequence Data; D008970:Molecular Weight; D050505:Mutant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D010802:Phylogeny; D055550:Protein Stability; D059748:Proteolysis; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D012995:Solubility; D013379:Substrate Specificity; D046940:Synechococcus / Q000201:enzymology* / Q000254:growth & development
chemical_list: D001426:Bacterial Proteins; D050505:Mutant Proteins; D011994:Recombinant Proteins; D000626:Aminopeptidases; D007930:Leucine
keywords: ClpS adaptor; N-end rule; Proteolysis; Synechococcus elongatus