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Structural and Dynamic Properties of Incomplete Immunoglobulin-like Fold Domains

[ Vol. 19 , Issue. 10 ]


Rita Berisio, Luciano Ciccarelli, Flavia Squeglia, Alfonso De Simone and Luigi Vitagliano   Pages 1045 - 1053 ( 9 )


The immunoglobulin fold (Ig-fold) is a widespread structural motif that is detected in a variety of proteins involved in diversified biological processes. The Ig-fold contains 70-110 residues that are assembled in a characteristic sandwich-like structure formed by two facing β-sheets each made of antiparallel β-strands. A number of variations on this common theme have been detected and described (Ig-like fold). One of the most intriguing variants is characterized by the lack of a strand compared to the canonical motif (incomplete Ig-like fold). Interestingly, proteins exhibiting incomplete Ig-like fold have been shown to play an important role in mediating either protein-protein or domain-domain interactions. Protein-protein interactions mediated by incomplete Ig-like folds play a key structural role in the chaperone–usher pathway, a process that generates multi-protein assemblies essential for the adhesion of gram negative bacteria. Domains with incomplete Ig-like fold have also been discovered in the mechanism of action of adhesins belonging to the family of MSCRAMMs (microbial surface components recognizing adhesive matrix molecules). Recently, a stable incomplete Iglike fold has been detected in the peptidoglycan-binding extra-cellular portion of Staphylococcus aureus PrkC, an important Ser/Thr membrane kinase involved in bacterial growth and revival from latency. It is important to note that the occurrence of proteins with incomplete Ig-like fold is often related to cell adhesion and infectivity of bacterial pathological agents. We here report a survey of the structural data available on this peculiar structural motif highlighting analogies and differences of incomplete Ig-like fold involved in different processes. The dynamical behavior of these domains, investigated by molecular dynamics techniques, will be also commented.


Immunoglobulin fold, adhesins, MSCRAMM, pili, molecular dynamics


Istituto di Biostrutture e Bioimmagini C.N.R., Via Mezzocannone 16, I-80134 Napoli, Italy.

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