THE 75-KILODALTON ANTIGEN OF BARTONELLA-BACILLIFORMIS IS A STRUCTURALHOMOLOG OF THE CELL-DIVISION PROTEIN FTSZ

A genomic library of Bartonella bacilliformis was constructed and scre ened with human anti-Bartonella serum from a patient with the chronic, verruga peruana phase of bartonellosis. An immunoreactive clone isola ted from this library was found to code for a 591-amino-acid protein w ith a high degree of sequence similarity to the FtsZ family of protein s. The degree of amino acid identity between the B. bacilliformis prot ein (FtsZ(Bb)) and the other FtsZ proteins is especially pronounced ov er the N-terminal 321 amino acids (N-terminal domain) of the sequence, with values ranging from 45% identity for the homolog from Micrococcu s luteus (FtsZMl) to 91% identity for the homolog from Rhizobium melli loti, (FtsZ(Rm1)). All of the functional domains required for FtsZ act ivity are conserved in FtsZ(Bb) and are located within the N-terminal domain of the protein. FtsZ(Bb) is approximately twice as large as mos t of the other FtsZ proteins previously reported, a property it shares with FtsZ(Rm1). Like the Rhizobium homolog, FtsZ(Bb) has a C-terminal region of approximately 256 amino acids that is absent in the other F tsZ proteins. Evidence is presented that implicates this region in the protein's antigenicity and suggests that, unlike most other FtsZ homo logs, FtsZ(Bb) is at least partly exposed at the cell surface. PCR ana lysis revealed that an ftsZ gene similar in size to the B. bacilliform is gene is present in Bartonella henselae, a bacterium that is closely related to B. bacilliformis.