2-kb PCR product carrying dndB with

introduced NdeI and BamHI sites (with C-terminal His-tag) was amplified and cloned into pMD18-T to give pJTU68. Then the corresponding NdeI-BamHI DNA fragment from RepSox pJTU68 was introduced into pHZ1272 between the restriction sites NdeI and BamHI to give pJTU81. dndC expression vector: using pHZ1904 as template, and wlr7 and wlr11 as primers, a 1.5-kb PCR product carrying dndC with introduced NdeI and BamHI sites (with C-terminal His-tag) was amplified and cloned into pMD18-T to give pJTU72. Then dndC from pJTU72 was introduced into pHZ1272 between the restriction sites NdeI and BamHI to give pJTU86. dndD expression vector: using pHZ1904 as template, and dnd-1 and dnd-2 as primers, a 2.0-kb PCR product carrying dndD with introduced NdeI and BamHI sites was amplified, digested with the corresponding enzymes and cloned into pET15b to generate pHZ2893. Then dndD from pHZ2893 was introduced into pHZ1272 between the restriction sites NdeI and BamHI to give pJTU64. dndE expression vector: using pHZ1904 as template, and dndE-L and dndE-R as primers, a 0.4-kb PCR product carrying dndE with introduced NdeI site was amplified and cloned into pMD18-T to give pJTU180. Then dndE from pJTU180 was introduced into pHZ1272 after digestion with NdeI and BamHI to KU-57788 cell line give pJTU65. Over-expression and purification of DndD protein After IPTG induction, E. coli BL21 (DE3) containing

pHZ2893 over-expressed the DndD fusion protein with a His-tag at the N-terminal end. The fusion protein as inclusion bodies was further purified with an ÄKTA-fast protein liquid chromatography system (FPLC) (Amersham Pharmacia Biotech) and a 5-ml HiTrap chelating column (Amersham Pharmacia Biotech) under denaturing condition. The fusion protein was used for the production of rabbit anti-DndD polyclonal antibody. RT-PCR analysis of dnd genes Gemcitabine mw RNA extraction was according to the standard protocol of RNeasy Protect Bacteria Midi Kit from Qiagen Co. Ltd. RT-PCR experiments were performed according to the standard protocol of OneStep RT-PCR Kit from the same company. Primers are listed in Table 1. Acknowledgements We are very grateful to Prof. Sir David Nepicastat Hopwood, FRS for his continuous support

and encouragement throughout this study for many years, and help for the editing of the manuscript. The authors wish to thank the National Science Foundation of China (NSFC), the Ministry of Science and Technology 973 and 863 programs, the Ministry of Education of China, the Shanghai Municipal Council of Science and Technology and Shanghai Leading Academic Discipline Project for research supports. Electronic supplementary material Additional file 1: Additional table 1.Table displaying bacterial strains and plasmids. (DOC 56 KB) References 1. Hattman S: Unusual modification of bacteriophage Mu DNA. J Virol 1979,32(2):468–475.PubMed 2. Hattman S: Specificity of the bacteriophage Mu mom+ -controlled DNA modification. J Virol 1980,34(1):277–279.PubMed 3.