Gaimster Hannah, Alston Mark, Richardson David J, Gates Andrew J, Rowley Gary
School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
FEMS Microbiol Lett. 2018 Mar 1;365(5). doi: 10.1093/femsle/fnx277.
In oxygen-limited environments, denitrifying bacteria can switch from oxygen-dependent respiration to nitrate (NO3-) respiration in which the NO3- is sequentially reduced via nitrite (NO2-), nitric oxide (NO) and nitrous oxide (N2O) to dinitrogen (N2). However, atmospheric N2O continues to rise, a significant proportion of which is microbial in origin. This implies that the enzyme responsible for N2O reduction, nitrous oxide reductase (NosZ), does not always carry out the final step of denitrification either efficiently or in synchrony with the rest of the pathway. Despite a solid understanding of the biochemistry underpinning denitrification, there is a relatively poor understanding of how environmental signals and respective transcriptional regulators control expression of the denitrification apparatus. This minireview describes the current picture for transcriptional regulation of denitrification in the model bacterium, Paracoccus denitrificans, highlighting differences in other denitrifying bacteria where appropriate, as well as gaps in our understanding. Alongside this, the emerging role of small regulatory RNAs in regulation of denitrification is discussed. We conclude by speculating how this information, aside from providing a better understanding of the denitrification process, can be translated into development of novel greenhouse gas mitigation strategies.
在氧气受限的环境中,反硝化细菌可以从依赖氧气的呼吸作用转变为硝酸盐(NO3-)呼吸作用,其中NO3-会通过亚硝酸盐(NO2-)、一氧化氮(NO)和一氧化二氮(N2O)依次被还原为氮气(N2)。然而,大气中的N2O持续上升,其中很大一部分源自微生物。这意味着负责还原N2O的酶——一氧化二氮还原酶(NosZ),并不总是能高效地执行反硝化作用的最后一步,也无法与该途径的其他步骤同步进行。尽管我们对反硝化作用的生物化学原理有深入了解,但对于环境信号和相应的转录调节因子如何控制反硝化装置的表达,了解相对较少。这篇小型综述描述了模式细菌——脱氮副球菌中反硝化作用转录调控的现状,在适当的地方强调了其他反硝化细菌中的差异以及我们理解上的空白。与此同时,还讨论了小调节RNA在反硝化作用调控中的新作用。我们通过推测这些信息除了能让我们更好地理解反硝化过程外,如何转化为新型温室气体减排策略来结束本文。