7R6S

Crystal Structure of the Putative Bacteriophage Protein from Stenotrophomonas maltophilia

Summary for 7R6S

• Entry DOI: 10.2210/pdb7r6s/pdb
• Descriptor: Putative bacteriophage protein, SULFATE ION (3 entities in total)
• Functional Keywords: structural genomics, center for structural genomics of infectious diseases, csgid, unknown function
• Biological source: Stenotrophomonas maltophilia (strain K279a)
• Total number of polymer chains: 2
• Total formula weight: 74495.89

Authors

Minasov, G.,Shuvalova, L.,Kiryukhina, O.,Brunzelle, J.S.,Wiersum, G.,Satchell, K.J.F.,Center for Structural Genomics of Infectious Diseases (CSGID),Center for Structural Biology of Infectious Diseases (CSBID) (deposition date: 2021-06-23, release date: 2022-11-09, Last modification date: 2025-09-24)

Primary citation

Cobe, B.L.,Dey, S.,Minasov, G.,Inniss, N.,Satchell, K.J.F.,Cianciotto, N.P.
Bactericidal effectors of the Stenotrophomonas maltophilia type IV secretion system: functional definition of the nuclease TfdA and structural determination of TfcB.
Mbio, 15:e0119824-e0119824, 2024

PubMed Abstract: expresses a type IV protein secretion system (T4SS) that promotes contact-dependent killing of other bacteria and does so partly by secreting the effector TfcB. Here, we report the structure of TfcB, comprising an N-terminal domain similar to the catalytic domain of glycosyl hydrolase (GH-19) chitinases and a C-terminal domain for recognition and translocation by the T4SS. Utilizing a two-hybrid assay to measure effector interactions with the T4SS coupling protein VirD4, we documented the existence of five more T4SS substrates. One of these was protein 20845, an annotated nuclease. A mutant lacking the gene for 20845 was impaired for killing , , and . Moreover, the cloned 20845 gene conferred robust toxicity, with the recombinant being rescued when 20845 was co-expressed with its cognate immunity protein. The 20845 effector was an 899 amino-acid protein, comprised of a GHH-nuclease domain in its N-terminus, a large central region of indeterminant function, and a C-terminus for secretion. Engineered variants of the 20845 gene that had mutations in the predicted catalytic site did not impede , indicating that the antibacterial effect of 20845 involves its nuclease activity. Using flow cytometry with DNA staining, we determined that 20845, but not its mutant variants, confers a loss in DNA content of target bacteria. Database searches revealed that uncharacterized homologs of 20845 occur within a range of bacteria. These data indicate that the T4SS promotes interbacterial competition through the action of multiple toxic effectors, including a potent, novel DNase.IMPORTANCE is a multi-drug-resistant, Gram-negative bacterium that is an emerging pathogen of humans. Patients with cystic fibrosis are particularly susceptible to infection. In hospital water systems and various types of infections, co-exists with other bacteria, including other pathogens such as . We previously demonstrated that has a functional VirB/D4 type VI protein secretion system (T4SS) that promotes contact-dependent killing of other bacteria. Since most work on antibacterial systems involves the type VI secretion system, this observation remains noteworthy. Moreover, currently stands alone as a model for a human pathogen expressing an antibacterial T4SS. Using biochemical, genetic, and cell biological approaches, we now report both the discovery of a novel antibacterial nuclease (TfdA) and the first structural determination of a bactericidal T4SS effector (TfcB).

PubMed: 38832773
DOI: 10.1128/mbio.01198-24

Experimental method

X-RAY DIFFRACTION (1.9 Å)