strain PCC 7120/hoxW/NP_484813 HoxWN7120 3d hoxH BAB72723.1 [63] Nostoc sp. strain PCC 7120/hupW/NP_485466 HupWN7120 2 hupL BAB72634.1 [63] Pyrococcus furiosus DSM 3638/hycI/AAL80741 HycIPf 4     [79] Ralstonia GS-7977 concentration eutropha H16/hoxM/AAP85761 HoxMReH16 1     [85] Ralstonia eutropha H16/hoxW/CAA63575 HoxWReH16 3d     [85] Ralstonia eutropha H16/PHG070/AAP85823 ReH16 –     [15] Rhizobium leguminosarum bv. Viciae/hupD/P27649 HupDRl 1     [75]

Salmonella enterica subsp. enterica serovar Choleraesuis str. SC-B67/hyaD/AAX65690 HyaDSe 1     [71] Salmonella enterica subsp. enterica serovar Choleraesuis str. SC-B67/hupD/AAX65459 Fosbretabulin concentration HupDSe 1     [71] Salmonella enterica subsp. enterica serovar Choleraesuis str. SC-B67/hybD/AAX66993 HybDSe 1     [71] Salmonella enterica subsp. enterica serovar Choleraesuis str. SC-B67/hycI/AAX66684.1 HycISe 4     [71] Shigella boydii Sb227/hyaD/ABB66821 HyaDSb 1     [87] Shigella boydii Sb227/hybD/ABB67388 GDC 0032 cell line HybDSb 1     [87] Shigella boydii Sb227/hycI/ABB67327 HycISb 4     [87] Synechococcus sp. strain PCC 7002/hoxW/AAN03570.1 HoxWS7002 3d       Synechocystis sp. strain PCC 6803/hoxW/BAA17680.1 HoxWS6803

3d     [76, 77] Thiocapsa roseopersicina/-/AY214929 HoxWTr 3d     [72] Thiocapsa roseopersicina/hupD/Q56362 HupDTr 1     [80] Thiocapsa roseopersicina/hydD-hynD/AAN87047.1 HynDTr –     [82] aAs used in phylogenetic tree (Figure

1). Hydrogenases shown in the table do not represent the total number of hydrogenases in each organism. Abbreviations; H2ase; hydrogenase, ref: reference. Searches for homologues sequences of Npun_F0373 (Nostoc punctiforme), Alr1422 (Nostoc PCC 7120) and promoter regions were done by both using the NCBI and CyanoBase databases and their respective BLAST programs. Prediction of DNA secondary structure was done by using the online program MFold [97, 98]. Transmembrane regions were predicted using the online program SOSUI [99–101]. For location studies of conserved residues on the surface of the proteases, alignments were performed for three of the protease groups revealed in the phylogenetic tree; group 5 – proteases Bumetanide of HoxW type (HoxW from Nostoc PCC 7120,Anabaena variabilis ATCC 29413,Lyngbya sp. strain PCC 8106, Ralstonia eutropha H16,Thiocapsa roseopersicina, Synechococcus sp. strain PCC 7002,Synechocystis sp. strain PCC 6803, Mycobacterium vanbaalenii PYR-1, and Methylococcus capsulatus strain Bath), group 2- cyanobacterial proteases of HupW type (HupW from Nostoc PCC 7120, Nostoc punctiforme, Lyngbya sp. strain PCC 8106, Anabaena variabilis ATCC 29413, Nodularia spumigena CCY 9414 and Gloeothece sp. strain PCC 6909) and group 1- proteases of HybD type (HupD/Azoarcus sp.