The cnm genomic locus in Streptococcus mutans contains two additional putative surface proteins. (A) In all cnm+ strains of S. mutans, cnm is located within a unique 5-kbp region between the core genes SMU_2067 and SMU_2069. SMU_2067 encodes a putative glycosyltransferase whereas SMU_2069 encodes the integral membrane zinc transporter ZupT. Two additional open reading frames (cnaB and cbpA) were identified upstream of cnm. Semi-quantitative RT-PCR analysis showed the co-transcription of cnaB with cbpA, whereas cnm was not part of this transcript. Presence of putative Rho-independent transcriptional terminator is indicated with a lollypop symbol. (B) Predicted domains of CnaB, CbpA and Cnm: SS, secretion signal; A, collagen-binding domain; B, threonine-rich repeats; LPXTG, cell-wall anchor motif.