Family 9.B.11 - The Mitochondrial mRNA Splicing-2 Protein Family
Family ID: 53386
MRS2 of Saccharomyces cerevisiae is essential for the splicing
of group II introns from RNA in mitochondria, and independently,
for the maintenance of a functional respiratory system. MRS2 is
an integral protein of the inner mitochondrial membrane. It exhibits
two adjacent putative TMSs in its C-terminal half. The large N-terminal
domain and a shorter C-terminal domain are probably localized
to the mitochondrial matrix. Structural features and a short sequence
motif suggest that MRS2 may be related to the E. coli CorA protein
and members of the MIT family (TC #2.A.45) which may function
as channels or carriers. Null mutations in the mrs2 gene have
mitochondria with low internal Mg2+ concentrations, and overexpression
of the E. coli corA gene in yeast partially supresses the mrs2
phenotype; CorA also partially restores intramitochondrial Mg2+
concentrations. These results suggest that MRS2 may be a mitochondrial
Mg2+ uptake system, involved in Mg2+ homeostasis. PSI-BLAST searches
with iterations to convergence do not reveal a connection between
MRS2 and the E. coli CorA protein. Consequently, these proteins
are maintained in seperate families. MRS2 in demonstrably homologous
to another S. cerevisiae ORF (YPL060w), an S. pombe ORF, and an
Arabidopsis thaliana ORF.
