in 0305w8-36 is the adjacent orf201, originally annotated8 as a association. If so, the genes in the 0305w8-36 version of this VirD4-like protein, based on the closest annotated sequences operon should include at least one orf that encodes a protein found by PsiBlast. More detailed analysis revealed that the with a membrane attachment site. For the following reasons, similarity is confined to a C-terminal ATPase domain. Query with we conclude that orf203 and orf207 are orfs of this type. Orf203 this domain hits Pfam family AAA_10, an ATPase domain is homologous to the virB6 locus, which encodes a membrane- frequently found in conjugation-associated ATPases (annotator’s associated protein that interacts with the DNA mobilization comments; PF12846). complex and the sex pilus during Ti plasmid-mediated conjuga- However, 0305w8-36 orf201 differed from both VirD4 and tion.25 Orf207 is homologous to mreB, which encodes a bac- mobB in not having a N-terminal domain composed primarily terial protein that is structurally homologous to actin and that of transmembrane helix. The N-terminal domain of 0305w8-36 associates with the cell membrane where it influences cell orf201 had no detectable transmembrane helical segment. To shape and is an anchor for another arm of the DNA translocase determine whether this absence of a transmembrane helical family involved in chromosome segregation.26,27 Thus, the segment occurs in other, similar genes, we searched for genes translocation operon includes orfs 200, 201, 203 and 207, no similar to 0305w8-36 orf201 and found them among genes hit two of which have homologs from a single known bacterial by queries from family models of both 0305w8-36 orf201 and operon. a homolog, ING1 (Table 2, rows 10 and 11), the latter also a However, we found that a partial version of a similar 0305w8- homolog of the traG translocase. Although traG has a N-terminal 36 DNA translocation operon does exist in other bacteriophages, transmembrane helix domain,23,24 about 75% of hits from queries based initially on hits from both entire relaxase genes and their with both ING1 and 0305w8-36 orf201 models had no trans- C-terminal segments. The data for the following bacteriophages ©orf200 membrane an2d201 helices 0appear (not 1tohave shown). 2arelativLely Thus, (1) the staandard absence norgandizationefor of a trans- are seither in Figure tBheentiriegoene 2 (bacteriophage, or sthe Cc-termiinal followed edomnain): in succession (c1)Baecillus by gi . membrane domain is not unusual among translocases and (2) number, orf number and the row(s) in Table 2 that have data to be the core of a conjugation relaxase/translocase operon. subtilis bacteriophage SP01 (209972955; 27.3; rows 4–5), Completion of the operon: Membrane attachment sites. (2) Geobacillus bacteriophage GBSV1 (158267614; 43; row 6), Mobilization complexes have to make an association with the (3) Bacillus virus 1 (155042415; 40; row 7), (4) Bacillus anthracis membrane-bound conjugation system in order to function. bacteriophage Gamma (77020183; orf not numbered; row 8) and mandate that a sepDarate porotein(s) nproviodesfotrmemdbraneisWBetta(drata niot bshownu).te. Hence, the absence of a transmembrane domain in orf201 might (5) close relatives of Gamma, including Cherry, Fah22 and Figure 2. Homologs of genes from the proposed DNA translocation operon of bacteriophage 0305w8-36. The plasmid or bacteriophage name is at the left. The NCBI accession number is above an arrow. The orf number is within an arrow, when given at the NCBI site. The family of some orfs is below the arrow and orf number. The functions of homologs in a given column are at the top in red. All distances are proportional to physical distances. 28 Bacteriophage Volume 2 Issue 1