Isolation,gene structure,and comparative analysis of the S-layer gene <Emphasis Type="Italic">sslA</Emphasis> of <Emphasis Type="Italic">Sporosarcina ureae</Emphasis> ATCC 13881 |
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Authors: | Pavel M Ryzhkov Kai Ostermann Gerhard Rödel |
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Institution: | 1.Institut für Genetik,Technische Universit?t Dresden,Dresden,Germany;2.Institut für Genetik,Technische Universit?t Dresden,Dresden,Germany |
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Abstract: | The surface (S)-layer of Sporosarcina ureae strain ATCC 13881, a periodic ordered structure with p4 square type symmetry, was recently reported to be an excellent biotemplate
for the formation of highly ordered metal clusters. The S-layer is formed by self-assembly of a single subunit, the 116 kDa
SslA protein. Here we report on the isolation and sequence analysis of the sslA gene. The protein sequence reveals a high degree of similarity to the sequences of other S-layer proteins that form self-assembly
lattices with the p4 square type symmetry, especially to those of Bacillus sphaericus. Two conserved surface layer homology (SLH) domains in the extreme aminoterminal portion are likely to mediate attachment
of the protein to secondary cell wall polymers. A central HisXXXHis motif and a cysteine residue in the carboxyl-terminal
part of the protein, both extremely rare in S-layer proteins, may contribute to the high affinity for metal ions. The strong
bias in the codon usage may explain that heterologous expression of SslA in E. coli is not very intense. With respect to the regulatory region we notice several features that are also present in other S-layer
genes. The distance between the −35/−10 region and the ATG initiation codon is unusually long, and a 41 bp palindromic sequence
is present in the immediate vicinity of the −35/−10 region. |
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Keywords: | Surface layer Sporosarcina ureae sslA SLH domain Self-assembly Heterologous expression |
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