Title
Structural Analysis of a Repetitive Protein Sequence Motif in Strepsirrhine Primate Amelogenin
Author
Rodrigo S. Lacruz, Rajamani Lakshminarayanan, Keith M. Bromley, Joseph G. Hacia, Timothy G. Bromage, Malcolm L. Snead, Janet Moradian-Oldak, Michael L. Paine
Year
2011
Journal
PLoS ONE
Abstract
Strepsirrhines are members of a primate suborder that has a distinctive set of features associated with the development of the dentition. Amelogenin (AMEL), the better known of the enamel matrix proteins, forms 90% of the secreted organic matrix during amelogenesis. Although AMEL has been sequenced in numerous mammalian lineages, the only reported strepsirrhine AMEL sequences are those of the ring-tailed lemur and galago, which contain a set of additional proline-rich tandem repeats absent in all other primates species analyzed to date, but present in some non-primate mammals. Here, we first determined that these repeats are present in AMEL from three additional lemur species and thus are likely to be widespread throughout this group. To evaluate the functional relevance of these repeats in strepsirrhines, we engineered a mutated murine amelogenin sequence containing a similar proline-rich sequence to that of Lemur catta. In the monomeric form, the MQP insertions had no influence on the secondary structure or refolding properties, whereas in the assembled form, the insertions increased the hydrodynamic radii. We speculate that increased AMEL nanosphere size may influence enamel formation in strepsirrhine primates.
Instrument
J-810
Keywords
Circular dichroism, Secondary structure, Protein folding, Thermal stability, Kinetics, Chemical stability, Biochemistry