title: Genes and derived amino acid sequences of S-layer proteins from mesophilic, thermophilic, and extremely thermophilic methanococci.
abstract: Cells of methanococci are covered by a single layer of protein subunits (S-layer) in hexagonal arrangement, which are directly exposed to the environment and which cannot be stabilized by cellular components. We have isolated S-layer proteins from cells of Methanococcus vannielii ( T(opt.)=37 degrees C), Methanococcus thermolithotrophicus ( T(opt.)=65 degrees C), and Methanococcus jannaschii ( T(opt.)=85 degrees C). The primary structure of the S-layer proteins was determined by sequencing the corresponding genes. According to the predicted amino acid sequence, the molecular masses of the S-layer proteins of the different methanococci are in a small range between 59,064 and 60,547 Da. Compared with its mesophilic counterparts, it is worth noting that in the S-layer protein of the extreme thermophile Mc. jannaschii the acidic amino acid Asp is predominant, the basic amino acid Lys occurs in higher amounts, and Cys and His are only present in this organism. Despite the differences in the growth optima and the predominance of some amino acids, the comparative total primary structure revealed a relatively high degree of identity (38%-45%) between the methanococci investigated. This observation indicates that the amino acid sequence of the S-layer proteins is significantly conserved from the mesophilic to the extremely thermophilic methanococci.
authors.affiliation: Institut für Mikrobiologie und Weinforschung, Johannes Gutenberg-Universität, 55099 Mainz, Germany.
authors.forename: Erol
authors.initials: E
authors.lastname: Akca
authors.forename: Harald
authors.initials: H
authors.lastname: Claus
authors.forename: Nina
authors.initials: N
authors.lastname: Schultz
authors.forename: Gilbert
authors.initials: G
authors.lastname: Karbach
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schlott
authors.forename: Tony
authors.initials: T
authors.lastname: Debaerdemaeker
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Declercq
authors.forename: Helmut
authors.initials: H
authors.lastname: König
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000235:genetics* / Q000502:physiology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D005798:Genes, Bacterial; D017017:Methanococcus / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013696:Temperature
chemical_list: D019843:Archaeal Proteins; D001425:Bacterial Outer Membrane Proteins