Gene products and processes contributing to lanthanide homeostasis and methanol metabolism in Methylorubrum extorquens AM1
Gene products and processes contributing to lanthanide homeostasis and methanol metabolism in Methylorubrum extorquens AM1
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DOI：
10.1038/s41598-020-69401-4
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发表时间：
2020-07-29
影响因子：
4.6
通讯作者：
Skovran, Elizabeth
中科院分区：
文献类型：
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作者：
Roszczenko-Jasinska, Paula;Vu, Huong N.;Skovran, Elizabeth
镧系元素最近被认为是“新生命金属”，但关于镧系元素的获取和体内平衡仍有许多未知之处。在扭脱甲基红菌AM 1中，周质镧系元素依赖性甲醇脱氢酶XoxF 1产生甲醛，如果允许积累，甲醛是致命的。这种特性使得转座子诱变研究和生长研究能够确认XoxF 1功能所需的新基因产物。所确定的基因编码MxaD同源物，ABC型转运蛋白，氨肽酶，推定的homospermidine合酶，和两个未知功能的基因注释为orf 6和orf 7。还鉴定了镧系元素转运和贩运基因。生长和镧系元素的吸收进行了测量，使用缺乏个别镧系元素运输簇基因的菌株，和透射电子显微镜被用来可视化镧系元素的定位。我们证实了以前的报告，TonB-ABC运输系统是必需的镧系元素掺入细胞质。然而，随着时间的推移，细胞能够适应并绕过TonB外膜转运蛋白的要求，以允许xoxF 1的表达和生长。转录报告融合表明，过量的镧系元素抑制的基因编码的TonB受体。使用生长研究沿着与能量色散X-射线光谱和透射电子显微镜，我们表明，镧系元素被存储为类似于聚磷酸盐颗粒的细胞质内含物。
Lanthanide elements have been recently recognized as "new life metals" yet much remains unknown regarding lanthanide acquisition and homeostasis. In Methylorubrum extorquens AM1, the periplasmic lanthanide-dependent methanol dehydrogenase XoxF1 produces formaldehyde, which is lethal if allowed to accumulate. This property enabled a transposon mutagenesis study and growth studies to confirm novel gene products required for XoxF1 function. The identified genes encode an MxaD homolog, an ABC-type transporter, an aminopeptidase, a putative homospermidine synthase, and two genes of unknown function annotated as orf6 and orf7. Lanthanide transport and trafficking genes were also identified. Growth and lanthanide uptake were measured using strains lacking individual lanthanide transport cluster genes, and transmission electron microscopy was used to visualize lanthanide localization. We corroborated previous reports that a TonB-ABC transport system is required for lanthanide incorporation to the cytoplasm. However, cells were able to acclimate over time and bypass the requirement for the TonB outer membrane transporter to allow expression of xoxF1 and growth. Transcriptional reporter fusions show that excess lanthanides repress the gene encoding the TonB-receptor. Using growth studies along with energy dispersive X-ray spectroscopy and transmission electron microscopy, we demonstrate that lanthanides are stored as cytoplasmic inclusions that resemble polyphosphate granules.