Ca-binding and spectral properties of the common region of surface-exposed Lig proteins of leptospira.

Pathogenic Leptospira protein LigA and LigB are conserved at the N-terminal sequence. In our earlier report, we have presented the spectral properties of individual Big domain of Lig proteins, and showed that an individual domain binds Ca(2+). Here we demonstrate that apart from Ca(2+)-binding properties, the spectral properties (such as doublet Trp fluorescence) shown by an individual domain are almost retained in the protein with many such domains (which could easily be called a multimer of an individual tandem repeat). Presence of Asp and Asn in a stretch of sequence in all tandem repeats points towards the possibility of their involvement in Ca(2+)-binding.