Carboxysomes are extremely efficient microcompartments committed to CO2 fixation due to tailored CO2-concentrating mechanism (CCM). In cyanobacteria and some chemoautotrophs, carboxysomes as organelle-like microbodies encapsulate ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and carbonic anhydrase (CA). Together with active inorganic carbon uptake transporters, carboxysomes accumulate HCO3(-) in the cytoplasm, leading to high efficiency of carbon fixation. Based on the elucidation of structures and functionalities, heterologous production of carboxysomes has been achieved so far. In fact, the genes encoding either vacant carboxysome shell or only interior components have been characterized. This review summarizes the discovery along with types, showcases molecular structures and roles of carboxysomes in CCM, and presents their broad applications in metabolic engineering.
Biological Transport ; Carbon ; metabolism ; Carbon Cycle ; Carbon Dioxide ; metabolism ; Cyanobacteria ; metabolism ; Metabolic Engineering

Objective To compare the extraction methods of cellulose enzyme,semi-bionic and alcohol reflux for the impact of aconitine and aconitum alkaloids yields,and to optimize the extraction method. Methods The optimum condition of enzymatic extraction has been obtained by orthogonal test and compared with semi-bionic and alcohol reflux extraction by taking the contents of aconitine and aconitum alkaloids as indexes.Results The optimum extraction conditions were as follows:the temperature was 45℃, pH value was 4.5,the amount of cellulose enzyme was 8 mg/g,the extracting time was 5 h and the extraction rate of aconitine was 0.002 447%,aconitum alkaloids was 0.244 410%.The extraction rates of aconitine and aconitum alkaloids of semi-bionic extraction were 0.001 735%and 0.189 340%,respectively. The extraction rates of aconitine and aconitum alkaloids of alcohol reflux extraction were 0.001 869% and 0.200 720%respectively.The enzymatic extraction has a significant advantage.Conclusion The enzymatic extraction significantly improve the extraction rates of aconitine and aconitum alkaloids,it could be applied in practice.

The rice Rim2/Hipa is a stress-induced transposon superfamily recently identified in Oryza genomes. Genomic variation was found in the Rim2 core region among rice genetic resources/genomes, indicative of high genomic divergence accumulated during the Rim2 evolution. Based on the divergence and quiescent state of the Rim2 elements, a Rim2 paralog display-based fingerprinting approach was developed to effectively identify rice genetic resources and explore their genetic relationships within a set of rice germplasm including 45 accessions ofO. sativa and 8 accessions of its wild relatives O. rufipogon. A dendrogram showed not only clear genetic diversity of rice germplasm, but also considerable genetic differentiation among wild rice resources. The wild rice relatives were either clustered as an independent group, or among the japonica varieties. This Rim2-based fingerprinting approach could also serve as a sensitive tool to identify rice hybrids from their parents, and variety stability, demonstrating its great potential in evolution study ofrice genomes and in rice breeding and seed production.

As a naturally occurring steroid sapogenin, diosgenin acts as the precursor of hundreds of steroid medicines, and thereby has important medicinal value. Currently, industrial production of diosgenin relies primarily on chemical extraction from plant materials. Clearly, this strategy shows drawbacks of excessive reliance on plant materials and farmland as well as environment pollution. Due to development of metabolic engineering and synthetic biology, bio-production of diosgenin has garnered plenty of attention. Although the biosynthetic pathways of diosgenin have not been completely identified, in this review, we outline the identified biosynthetic pathways and key enzymes. In particular, we suggest heterologous biosynthesis of diosgenin in Saccharomyces cerevisiae. Overall, this review aims to provide valuable insights for future complete biosynthesis of diosgenin.
Biosynthetic Pathways/genetics* ; Diosgenin ; Metabolic Engineering