S-layer proteins are an issue of arising interest due to their ability to form periodical self-assembly nanopore structures. In this work we analyze the self-assembly potential of the recently characterized SslA S-layer protein of Sporosarcina ureae and of truncated SslA derivatives. The SslA protein with an estimated molecular weight of 116 kDa is shown to self-assemble in vitro into the periodic lattices with parameters identical to those of native S-layers formed on the surface of bacterial cells. Recombinant SslA proteins with truncation of N-, C-, or both N- and C-terminal parts were successfully overexpressed in E. coli and showed an aggregation behavior in vitro. A HisXXXHis motif in the central protein part is likely to contribute to self-assembly through the coordination of adjacent SslA monomers by binding the procurable divalent metal ions. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.