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We have determined the crystal structure of hypothetical protein TTHB192 from Thermus thermophilus HB8 at 1.9 Å resolution. This protein is a member of the Escherichia coli ygcH sequence family, which contains ∼15 sequence homologs of bacterial origin. These homologs have a high isoelectric point. The crystal structure reveals that TTHB192 consists of two independently folded domains, and that each domain exhibits a ferredoxin‐like fold with a four‐stranded antiparallel β‐sheet packed on one side by α‐helices. These two tandem domains face each other to generate a β‐sheet platform. TTHB192 displays overall structural similarity to Sex‐lethal protein and poly(A)‐binding protein fragments. These proteins have RNA binding activity which is supported by a β‐sheet platform formed by two tandem repeats of an RNA recognition motif domain with signature sequence motifs on the β‐sheet surface. Although …