Sel1-like repeat proteins in signal transduction

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Solenoid proteins, characterized by modular architectures, are key in signal transduction.
• Tetratricopeptide repeat (TPR) and Sel1-like repeat (SLR) proteins share alpha-helical structures but differ in sequence and topology.
• Low sequence similarity in SLR proteins complicates functional homology identification.

Purpose of the Study:

• To review the molecular and cellular functions of various Sel1-like repeat (SLR) proteins.
• To understand the role of SLR proteins as adaptors in macromolecular complex assembly.
• To explore the evolutionary origins and distribution of the SLR motif.

Main Methods:

• Literature review of existing research on SLR proteins.
• Comparative analysis of structural and functional characteristics of SLR proteins.
• Examination of the presence and absence of the SLR motif across different domains of life.

Main Results:

• SLR proteins function as adaptors, facilitating macromolecular complex assembly.
• Specific SLR proteins (Sel1, Hrd3, Hsp12, LpnE) are activated under cellular stress.
• Eukaryotic SLR proteins (Sel1, Hrd3) are involved in ER-associated protein degradation, while bacterial SLR proteins mediate host-cell interactions.
• SLR proteins are implicated in diverse functions including bacterial entry, exopolysaccharide synthesis, mitosis, and cell differentiation.
• The SLR motif links signal transduction pathways in eukaryotes and bacteria and is absent in archaea.

Conclusions:

• The Sel1-like repeat (SLR) motif serves as a crucial link between eukaryotic and bacterial signal transduction.
• SLR proteins exhibit diverse cellular functions, primarily acting as adaptors for complex assembly.
• The evolutionary origin of the SLR motif likely predates the divergence of eukaryotes and bacteria.