Disease relevance of SAMM50

• In line with this, the affinity of the N-terminal domain to the C-terminal region of the Omp85 from plastids and cyanobacteria differs, even though the N-terminal domain is involved in gating of the pore in both groups [1].
• This finding can explain why Omp85 from cyanobacteria (but not the homologous protein from proteobacteria) was remodeled to become the protein translocation pore after endosymbiosis [1].
• Omp85 is a protein found in Gram-negative bacteria where it serves to integrate proteins into the bacterial outer membrane [2].
• We have employed a maximum likelihood and a maximum parsimony approach to detect evidence of positive Darwinian selection in Omp85 homologues from 10 delta-proteobacteria and have identified 14 amino acid sites that show evidence of being under the influence of adaptive evolution [3].
• To study its molecular mechanism, we have produced Omp85 from Escherichia coli in inclusion bodies and refolded it in vitro [4].

High impact information on SAMM50

• The key component of this pathway is Tob55 (also known as Sam50) in mitochondria and Omp85 in bacteria, both beta-barrel membrane proteins themselves [5].
• beta-Barrel-shaped channels of the Omp85 family are involved in the translocation or assembly of proteins of bacterial, mitochondrial, and plastidic outer membranes [1].
• Nevertheless, we show that Tom40 assembly is reduced in mitochondria depleted of human Sam50 [6].
• The widespread distribution of Omp85 family members together with their fundamental role in outer membrane assembly suggests the ancestral Omp85 arose early in the evolution of prokaryotic cells [2].
• Evidence of positive Darwinian selection in Omp85, a highly conserved bacterial outer membrane protein essential for cell viability [3].

Biological context of SAMM50

• Development of the envelope translocon was initiated by recruitment of a cyanobacterial homolog of the protein-import channel Toc75, which belongs to a ubiquitous and essential family of Omp85/D15 outer membrane proteins of gram-negative bacteria that mediate biogenesis of beta-barrel proteins [7].

References