Photosynthetic organisms have developed various light-harvesting antenna systems to capture light and transfer energy to reaction centers(RCs).Simultaneous utilization of the integral membrane light-harvesting antenna...Photosynthetic organisms have developed various light-harvesting antenna systems to capture light and transfer energy to reaction centers(RCs).Simultaneous utilization of the integral membrane light-harvesting antenna(LH complex)and the extrinsic antenna(chlorosomes)makes the phototrophic bacterium Chloroflexus(Cfx.)aurantiacus an ideal model for studying filamentous anoxygenic phototrophs(FAPs).Here,we determined the structure of a minimal RC-LH photocomplex from Cfx.aurantiacus J-10-fl(CaRC-LH)at 3.05-Åresolution.The CaRC-LH binds only to seven LH subunits,which form a crescent-shaped antenna surrounding the movable menaquinone-10(QB)binding site of CaRC.In this complex with minimal LH units,an extra antenna is required to ensure sufficient light-gathering,providing a clear explanation for the presence of chlorosomes in Cfx.aurantiacus.More importantly,the semicircle of the antenna represents a novel RC-LH assembly pattern.Our structure provides a basis for understanding the existence of chlorosomes in Cfx.aurantiacus and the possible assembly pattern of RC-LH.展开更多
基金funded by the National Natural Science Foundation of China(32270260,32070267,32200206,32241030,and 32271245)the Taishan Scholars Project(tsqn20240516)the Shandong Provincial Natural Science Foundation,China(ZR2019ZD48 and ZR2020QC057).
文摘Photosynthetic organisms have developed various light-harvesting antenna systems to capture light and transfer energy to reaction centers(RCs).Simultaneous utilization of the integral membrane light-harvesting antenna(LH complex)and the extrinsic antenna(chlorosomes)makes the phototrophic bacterium Chloroflexus(Cfx.)aurantiacus an ideal model for studying filamentous anoxygenic phototrophs(FAPs).Here,we determined the structure of a minimal RC-LH photocomplex from Cfx.aurantiacus J-10-fl(CaRC-LH)at 3.05-Åresolution.The CaRC-LH binds only to seven LH subunits,which form a crescent-shaped antenna surrounding the movable menaquinone-10(QB)binding site of CaRC.In this complex with minimal LH units,an extra antenna is required to ensure sufficient light-gathering,providing a clear explanation for the presence of chlorosomes in Cfx.aurantiacus.More importantly,the semicircle of the antenna represents a novel RC-LH assembly pattern.Our structure provides a basis for understanding the existence of chlorosomes in Cfx.aurantiacus and the possible assembly pattern of RC-LH.
