Recently,Cell invited Dr. She Qunxin at the CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Shandong University to write a Preview minireview to comment on a cutting-edge discovery in crenarchaeal 3D genome research published in the same issue of Cell(original research link: https://www.cell.com/cell/fulltext/S0092-8674(19)30955-9 ). Title of the preview article is “Crenarchaeal 3-D Genome: A Prototypical Chromosome Architecture for Eukaryotes”, and it is authored by Feng Xu, a Postdoctoral fellow of A Category, Huang Qihong, an Assistant Research Fellow and She Qunxin, a Distinguished Professor (corresponding author), with the State Key Laboratory of Microbial Technology as the sole research affiliation.
Hi-C chromosome conformation capture assay was discovered in 2009. The method was then rapidly applied in the study of higher-order chromosome organization in several representative organisms of bacteria and eukaryotes. The results have radically changed our view on the topology of eukaryotic chromosomes: while eukaryotic chromosomes are segregated into two distinct compartments called ‘‘A’’ and ‘‘B’’, the prokaryote, bacteria only form loop extrusion while chromosomal compartmentalization has never occurred. Accordingly, chromosome compartmentalization was thought as a eukaryotic feature. Furthermore, genes in the ‘‘A’’ compartment in eukaryotes are generally transcriptionally active, the genes in the ‘‘B’’ compartment are mostly transcriptionally inactive. Since such a strategy of genome regulation is apparently not needed in bacteria, chromosome compartmentalization was therefore ascribed as eukaryote-specific characteristic.
However, the Cell research article reports that the chromosomes of Sulfolobus, a crenarchaeon also undergo compartmentalization as in eukaryotes, and furthermore, the resulting compartments ‘‘A’’ and ‘‘B’’ are clustered, respectively, with transcriptionally more active genes and transcriptionally more less active genes, reminiscent of the higher-level chromosome organization in eukaryotes. These results, again, radically changed our view on 3D genome organization and their functions in prokaryotes and in eukaryotes because the line between prokaryotes and eukaryotes is diminished. Based on these discoveries, this Preview article starts with a brief summary on similarities and differences between the higher-level chromosome organization in bacteria and that in crenarchaea and eukaryote, which leads to the classification of organisms with known 3D genomes into two classes: (a) bacteria, and (b) crenarchaea and eukaryotes. Given crenarchaea possess eukaryotic type of cell cycle, the authors reason that the 3D genome topology discovered in crenarchaea may resemble the prototypical chromosome organization of eukaryote from which the sophisticated eukaryotic 3D genome has been derived. At the end of the preview, several important questions have been raised regarding to the molecular mechanisms of archaeal 3-D genome organization and their physiological functions, providing important guidelines for further study in the new research field.
The link of this paper:
Higher-Level Chromosome Organization in All Three Domains of Life
It is worth pointing out that, early on, She Qunxin was invited to write a “Voice” piece for Cell, and the resulting Cell feature article entitled “Empathy as a solution” represents one of the Voice pieces under the title of “Creating a unique culture” published in the May 30 issue of Cell, timed with this year’s annual meeting of the American Society of Microbiologists in San Francesco. The article link ishttps://www.cell.com/cell/fulltext/S0092-8674(19)30512-4.
Written by：She Qunxin，Yu Zhenxiao