FIG. 1.

Inferred physical map of the DNA sequence of the R. meliloti phn gene cluster (28) showing locations of the PCR primers used in this study (small arrows above the sequence) and the predicted protein products. The 2-kb Sp^r-Sm^r fragment from plasmid pHP45Ω (37) was inserted into the DNA cloned in pRMP1 as a SmaI fragment into the ClaI and NdeI sites blunted with the Klenow fragment of DNA polymerase I (40). This construct was inserted into the XbaI site of pJQ200SK to give pRMP4, which was conjugated into R. meliloti to gave the mutant strain Pn1.