| Magnetotatic bacteria(MTB) can synthetise nano-scale magnetosomes which are composed of Fe3O4. In order to explore the mechanism of magnetosomes biomineralization in Magnetospirillum gryphiswaldense MSR-1, a mutant strain which had no magnetic response was obtained by Tn5 random insertion and Tn5 inserted in mamZ gene by sequencing. mamZ is one gene of mamXY operon in magnetosome island(MAI). We intend to elucidate the role of this gene on cell growth and magnetosome synthesis process in this study.To clarify the function of mamZ, based on analysis of the mamZ gene structure and location, the mamZ deletion mutant(△mamZ) and four complemented strains with different truncated mamZ genes(CmamZ, CpmamZ, CMFS, and CredFe) were constructed. We found that the deletion of mamZ had no impact on cell growth,but led to the reduced magnetic response and iron absorption. The results of magnetic properties showed that the crystals of magnetosomes in △mamZ were small, irregular, and superparamagnetic particles. It was proved that mamZ gene plays an important role in the growth of magnetosomes biomineralization.The qPCR results showed that the relative transcription levels of mamY and ftsZ-like in △mamZ were higher than that in wild type(WT) and the relative transcription levels of mamX and ftsZ-like were higher at 18 h than 12 h in all strains. It indicated the functional complementation because of their co-localized in mamXY operon and the important role of mamXY operon in the maturity of magnetosomes. Besides, the relative transcription levels of mms6 in △mamZ, △mamX, and their complemented strains were significantly higher than that in WT, which implied there is some kind of interaction among mamZ, mamX, and/or mamXY operon and mms6.This study not only proved that mamZ participates in the process of crystal maturity and once again found the functional complementation among genes in mamXY operon. It is necessary to further study the relationships between MamXY and Mms6. |
PDF Full Text Request