6ZGN

Crystal structure of VirB8-like OrfG central domain of Streptococcus thermophilus ICESt3; a putative assembly factor of a gram positive conjugative Type IV secretion system.

Summary for 6ZGN

• Entry DOI: 10.2210/pdb6zgn/pdb
• Descriptor: Putative transfer protein (2 entities in total)
• Functional Keywords: ntf2-like, virb8-like, transport protein, type iv secretion system, gram positive
• Biological source: Streptococcus thermophilus
• Total number of polymer chains: 1
• Total formula weight: 16337.19

Authors

Cappele, J.,Mohamad-Ali, A.,Leblond-Bourget, N.,Payot-Lacroix, S.,Mathiot, S.,Didierjean, C.,Favier, F.,Douzi, B. (deposition date: 2020-06-19, release date: 2021-04-28, Last modification date: 2024-05-15)

Primary citation

Cappele, J.,Mohamad Ali, A.,Leblond-Bourget, N.,Mathiot, S.,Dhalleine, T.,Payot, S.,Savko, M.,Didierjean, C.,Favier, F.,Douzi, B.
Structural and Biochemical Analysis of OrfG: The VirB8-like Component of the Conjugative Type IV Secretion System of ICE St3 From Streptococcus thermophilus .
Front Mol Biosci, 8:642606-642606, 2021

PubMed Abstract: Conjugative transfer is a major threat to global health since it contributes to the spread of antibiotic resistance genes and virulence factors among commensal and pathogenic bacteria. To allow their transfer, mobile genetic elements including Integrative and Conjugative Elements (ICEs) use a specialized conjugative apparatus related to Type IV secretion systems (Conj-T4SS). Therefore, Conj-T4SSs are excellent targets for strategies that aim to limit the spread of antibiotic resistance. In this study, we combined structural, biochemical and biophysical approaches to study OrfG, a protein that belongs to Conj-T4SS of ICE from . Structural analysis of OrfG by X-ray crystallography revealed that OrfG central domain is similar to VirB8-like proteins but displays a different quaternary structure in the crystal. To understand, at a structural level, the common and the diverse features between VirB8-like proteins from both Gram-negative and -positive bacteria, we used an structural alignment method that allowed us to identify different structural classes of VirB8-like proteins. Biochemical and biophysical characterizations of purified OrfG soluble domain and its central and C-terminal subdomains indicated that they are mainly monomeric in solution but able to form an unprecedented 6-mer oligomers. Our study provides new insights into the structural analysis of VirB8-like proteins and discusses the interplay between tertiary and quaternary structures of these proteins as an essential component of the conjugative transfer.

PubMed: 33816557
DOI: 10.3389/fmolb.2021.642606

Experimental method

X-RAY DIFFRACTION (1.75 Å)