Metabolic Regulation Through Acetylation: Covalent modification of lysine residues in various proteins in the nucleus is a recognized mechanism for control of transcription. Now two papers suggest that acetylation may represent an important regulatory mechanism controlling the function of metabolic enzymes (see the Perspective by Norvell and McMahon ). Zhao et al. (p. 1000 ) found that a large proportion of enzymes in various metabolic pathways were acetylated in human liver cells. Acetylation regulated various enzymes by distinct mechanisms, directly activating some, inhibiting one, and controlling the stability of another. Control of metabolism by acetylation appears to be evolutionarily conserved: Wang et al. (p. 1004 ) found that the ability of the bacterium Salmonella entericum to optimize growth on distinct carbon sources required differential acetylation of key metabolic enzymes, thus controlling flux through metabolic pathways.

Amycolatopsis mediterranei is used for industry-scale production of rifamycin, which plays a vital role in antimycobacterial therapy. As the first sequenced genome of the genus Amycolatopsis, the chromosome of strain U32 comprising 10 236 715 base pairs, is one of the largest prokaryotic genomes ever sequenced so far. Unlike the linear topology found in streptomycetes, this chromosome is circular, particularly similar to that of Saccharopolyspora erythraea and Nocardia farcinica, representing their close relationship in phylogeny and taxonomy. Although the predicted 9 228 protein-coding genes in the A. mediterranei genome shared the greatest number of orthologs with those of S. erythraea, it was unexpectedly followed by Streptomyces coelicolor rather than N. farcinica, indicating the distinct metabolic characteristics evolved via adaptation to diverse ecological niches. Besides a core region analogous to that common in streptomycetes, a novel 'quasi-core' with typical core characteristics is defined within the non-core region, where 21 out of the total 26 gene clusters for secondary metabolite production are located. The rifamycin biosynthesis gene cluster located in the core encodes a cytochrome P450 enzyme essential for the conversion of rifamycin SV to B, revealed by comparing to the highly homologous cluster of the rifamycin B-producing strain S699 and further confirmed by genetic complementation. The genomic information of A. mediterranei demonstrates a metabolic network orchestrated not only for extensive utilization of various carbon sources and inorganic nitrogen compounds but also for effective funneling of metabolic intermediates into the secondary antibiotic synthesis process under the control of a seemingly complex regulatory mechanism.

Amycolatopsis orientalis is the type species of the genus and its industrial strain HCCB10007, derived from ATCC 43491, has been used for large-scale production of the vital antibiotic vancomycin. However, to date, neither the complete genomic sequence of this species nor a systemic characterization of the vancomycin biosynthesis cluster (vcm) has been reported. With only the whole genome sequence of Amycolatopsis mediterranei available, additional complete genomes of other species may facilitate intra-generic comparative analysis of the genus. The complete genome of A. orientalis HCCB10007 comprises an 8,948,591-bp circular chromosome and a 33,499-bp dissociated plasmid. In total, 8,121 protein-coding sequences were predicted, and the species-specific genomic features of A. orientalis were analyzed in comparison with that of A. mediterranei. The common characteristics of Amycolatopsis genomes were revealed via intra- and inter-generic comparative genomic analyses within the domain of actinomycetes, and led directly to the development of sequence-based Amycolatopsis molecular chemotaxonomic characteristics (MCCs). The chromosomal core/quasi-core and non-core configurations of the A. orientalis and the A. mediterranei genome were analyzed reciprocally, with respect to further understanding both the discriminable criteria and the evolutionary implementation. In addition, 26 gene clusters related to secondary metabolism, including the 64-kb vcm cluster, were identified in the genome. Employing a customized PCR-targeting-based mutagenesis system along with the biochemical identification of vancomycin variants produced by the mutants, we were able to experimentally characterize a halogenase, a methyltransferase and two glycosyltransferases encoded in the vcm cluster. The broad substrate spectra characteristics of these modification enzymes were inferred. This study not only extended the genetic knowledge of the genus Amycolatopsis and the biochemical knowledge of vcm-related post-assembly tailoring enzymes, but also developed methodology useful for in vivo studies in A. orientalis, which has been widely considered as a barrier in this field.

Asymmetric cell division (ACD) produces morphologically and behaviorally distinct cells and is the primary way to generate cell diversity. In the model bacteriumCaulobacter crescentus, the polarization of distinct scaffold-signaling hubs at the swarmer and stalked cell poles constitutes the basis of ACD. However, mechanisms involved in the formation of these hubs remain elusive. Here, we show that a swarmer-cell-pole scaffold, PodJ, forms biomolecular condensates both in vitro and in living cells via phase separation. The coiled-coil 4–6 and the intrinsically disordered regions are the primary domains that contribute to biomolecular condensate generation and signaling protein recruitment in PodJ. Moreover, a negative regulation of PodJ phase separation by the stalked-cell-pole scaffold protein SpmX is revealed. SpmX impedes PodJ cell-pole accumulation and affects its recruitment ability. Together, by modulating the assembly and dynamics of scaffold-signaling hubs, phase separation may serve as a general biophysical mechanism that underlies the regulation of ACD in bacteria and other organisms.

Improving photosynthetic efficiency is pivotal for biomanufacturing and agriculture. Despite the progress on photosynthetic biohybrids integrating biocatalysts with materials, nanomaterials with increasing energy-efficiency as well as great biocompatibility and cost-effectiveness are needed. Here, we present a closed-loop strategy using biomass-derived carbon dots (CDs) for improving photosynthesis. We demonstrate that the CDs act as both light converters and photosensitizers by converting solar irradiation to red light and supplying light-excited electrons into the photosynthetic electron transfer chain. Biohybrids incorporating CDs and cyanobacteria or plant exhibited increased photosynthetic efficiency, when compared with the photosynthetic organism only. The cyanobacterial CO₂-fixation rate and CO₂-to-glycerol production were increased 2.4-fold and 2.2-fold, respectively, while Arabidopsis thaliana displayed a 1.8-fold increase in the fresh weight of the plant. Techno-economic analysis showed the competitive advantage of biomass-derived CDs over other nanomaterials. These CDs hold potential applications in future sustainable agriculture and solar-powered biomanufacturing.