M*: 100 Base-Pair Ladder (GE Healthcare). Within the hoxE and xisH promoter regions the following regions are indicated: putative LexA binding sites, putative IHF binding sites (boxed with the mismatching nucleotide shaded), the -10 and -35 boxes and the ribosome binding site – RBS (underlined), the transcription start point (+1, bold and underlined), and the start codons of hoxE and xisH (bold and underlined).

Cotranscription of hoxEFUYH and hoxW, and hupSL and hupW To assess CP673451 the cotranscription of hox genes and to clarify if the genes encoding the hydrogenases-specific endopeptidases (hoxW and hupW) are cotranscribed with the respective structural genes, RT-PCR experiments were performed with RNA collected from Lyngbya majuscula cells grown in conditions in which the transcript levels were Captisol clinical trial demonstrated to be high (for details see Material and Methods, [1, 2]). The cDNAs were synthesized using a hoxH-, a hoxW- or a hupW-specific antisense primer, and amplifications were performed with primer pairs that covered regions between hoxEF, hoxF-hcp, hoxUY, hoxYH, ORF16-hoxW, hupSL and hupL-W. In all cases, PCR products were obtained (Fig. 1A, B, 2A and

2B). These data indicate that all the structural genes encoding the bidirectional hydrogenase, and the gene putatively encoding the hybrid cluster protein (hcp), can be transcribed as a single operon in L. majuscula. Amisulpride The results also show that hoxW is cotranscribed with ORF16 (Fig. 1B), ORF15, xisI and xisH (data not shown). The ORF14 is in the opposite direction in relation to the hox genes, and no PCR product was detected using the cDNA generated with hoxW-specific primer and ORF14 specific primers. In order

to assess the transcription of ORF14, RT-PCR was performed using cDNA synthesized with random primers, the only PCR product obtained was generated using a ORF14 internal primer pair suggesting that ORF14 is indeed transcribed as a monocistronic unit (data not shown). Concerning the uptake hydrogenase it has been previously demonstrated that the structural genes hupSL were cotranscribed [2], however until now the transcription of the gene encoding the putative specific endopeptidase -hupW – was not accessed. In this work, we demonstrated that hupW can be transcribed together with hupSL, although a promoter region upstream hupW was also identified (see Fig. 2C and text below). Figure 2 hup genes physical map, hupW promoter, and analysis of cotranscription in Lyngbya majuscula CCAP 1446/4. (A) Physical map of L. majuscula hup genes (JPH203 adapted from [3], accession number GenBank:AF368526), (B) analysis of the hup genes cotranscription by RT-PCR, and (C) nucleotide sequence of the promoter region upstream of hupW. A schematic representation of the cDNA and the products generated in the RT-PCRs is depicted below the physical map.