P II protein is essential for transcriptional regulation of anf gene cluster for iron-only nitrogenase in Rhodopseudomonas palustris

• DOI: 10.1128/aem.00465-25
• Publication Date: 2025-04-10T13:02:56Z
• Authors: Yan Zeng; Lingwei Cui; Mengmei Wang; Lu Huang; Mingyue Jiang; Ying Liu; Yongqiang Gao; Yanning Zheng
• Keywords: Rhodopseudomonas palustris; Gene cluster

ABSTRACT In addition to catalyzing the biological nitrogen fixation, iron-only (Fe-only) nitrogenase is also able reduce carbon dioxide (CO 2 ) formate (HCOO − and methane (CH 4 ). AnfA responsible for transcriptional activation of anf gene cluster Fe-only nitrogenase, whose expression repressed by fixed nitrogen. However, it remains unclear how regulated control nitrogenase. Here, we found that in Rhodopseudomonas palustris , P II proteins play a critical role regulating genes via AnfA. We hypothesize deuridylylated protein GlnK1, which was upregulated presence ammonium (NH + ), could inhibit activity forming potential AnfA-GlnK1 complex. This likely serves as fail-safe mechanism prevent R. from expressing when accidentally expressed under nitrogen-excess conditions. The uridylylated GlnK2 UMP response starvation, stimulated an active hexamer further activated nitrogen-fixing Mo-free study provides new insights into regulation . IMPORTANCE maturation are tightly ambient levels, limits persistence efficiency fixation. offers regulatory Understanding AnfA, activator cluster, provide strategies better Nitrogen-fixing bacteria constitutively express have be developed promising biofertilizers, their enhanced independent molybdenum availability soil.