A single amino acid change in the transmembrane domain of the VirB8 protein affects dimerization, interaction with VirB10 and Brucella suis virulence

► A variant VirB8 of B. suis with a point mutation G59W in the transmembrane domain has been studied. ► This mutation increases the stability of homodimers of this protein and heterodimers with VirB10. ► This variant is unable to restore the virulence of a virB8 deleted B. suis mutant. ► Similar results are found with the transmembrane variant A55W of A. tumefaciens VirB8. ► Interactions of VirB8 with VirB10 are likely as important as homodimerization of VirB8 for virulence.