Yuan YaoHongwei SunWurihanGegeheng...
126-140页查看更多>>摘要：Transcription attenuation in response to the availability of a specific amino acid is believed to be controlled by alternative configurations of RNA secondary structures that lead to the arrest of translation or the release of the arrested ribosome from the leader mRNA molecule.In this study,we first report a possible example of the DnaA-dependent riboswitch for transcription attenuation in Escherichia coli.We show that(i)DnaA regulates the transcription of the structural genes but not that of the leader hisL gene;(ii)DnaA might bind to rDnaA boxes present in the HisL-SL RNA,and subsequently attenuate the transcription of the operon;(iii)the HisL-SL RNA and rDnaA boxes are phylogenetically conserved and evolutionarily important;and(iv)the translating ribosome is required for deattenuation of the his operon,whereas tRNAHis strengthens attenuation.This mechanism seems to be phylogenetically conserved in Gram-negative bacteria and evolutionarily important.
Kun MengJin YangJuan XueJun Lv...
141-158页查看更多>>摘要：Salmonella Typhimurium creates an intracellular niche for its replication by utilizing a large cohort of effectors,including several that function to interfere with host ubiquitin signaling.Although the mechanism of action of many such effectors has been elucidated,how the interplay between the host ubiquitin network and bacterial virulence factors dictates the outcome of infection largely remains undefined.In this study,we found that the SPI-2 effector SseK3 inhibits SNARE pairing to promote the formation of a Salmonella-induced filament by Arg-GlcNAcylation of SNARE proteins,including SNAP25,VAMP8,and Syntaxin.Further study reveals that host cells counteract the activity of SseK3 by inducing the expression of the E3 ubiquitin ligase TRIM32,which catalyzes K48-linked ubiquitination on SseK3 and targets its membrane-associated portion for degradation.Hence,TRIM32 antagonizes SNAP25 Arg-GlcNAcylation induced by SseK3 to restrict Salmonella-induced filament biogenesis and Salmonella replication.Our study reveals a mechanism by which host cells inhibit bacterial replication by eliminating specific virulence factors.
Hongyu WuLi WangWenjuan WangZhugui Shao...
159-177页查看更多>>摘要：Candida albicans deploys a variety of mechanisms such as morphological switch and elicitor release to promote virulence.However,the intricate interactions between the fungus and the host remain poorly understood,and a comprehensive inventory of fungal virulence factors has yet to be established.In this study,we identified a C.albicans secretory effector protein Sce1,whose induction and secretion are associated with vagina-simulative conditions and chlamydospore formation.Sequence alignment showed that Sce1 belongs to a Pir family in C.albicans,which is conserved across several fungi and primarily characterized as a β-glucan binding protein in the Saccharomyces cerevisiae.Mechanically,Sce1 is primarily localized to the cell wall in a cleaved form as an alkali-labile β-1,3-glucan binding protein and plays a role in masking β-glucan in acidic environments and chlamydospores,a feature that might underline C.albicans'ability to evade host immunity.Further,a cleaved short form of Sce1 protein could be released into extracellular compartments and presented in bone marrow-derived macrophages infected with chlamydospores.This cleaved short form of Sce1 also demonstrated a unique ability to trigger the caspases-8/9-dependent apoptosis in various host cells.Correspondingly,genetic deletion of SCE1 led to dampened vaginal colonization of C.albicans and diminished fungal virulence during systemic infection.The discovery of Sce1 as a versatile virulence effector that executes at various compartments sheds light on the fungus-host interactions and C.albicans patho-genesis.
Yi ShuYongming WangZhongcheng WeiNing Gao...
178-189页查看更多>>摘要：Microbial lysis of dimethylsulfoniopropionate(DMSP)is a key step in marine organic sulfur cycling and has been recently demonstrated to play an important role in mediating interactions between bacteria,algae,and zooplankton.To date,microbes that have been found to lyse DMSP are largely confined to free-living and surface-attached bacteria.In this study,we report for the first time that a symbiont(termed"Rhodobiaceae bacterium HWgs001")in the gill of the marine scallop Argopecten irradians irradians can lyse and metabolize DMSP.Analysis of 16S rRNA gene sequences suggested that HWgs001 accounted for up to 93％of the gill microbiota.Microscopic observations suggested that HWgs001 lived within the gill tissue.Unlike symbionts of other bivalves,HWgs001 belongs to Alphaproteobacteria rather than Gammaproteobacteria,and no genes for carbon fixation were identified in its small genome.Moreover,HWgs001 was found to possess a dddP gene,responsible for the lysis of DMSP to acrylate.The enzymatic activity of dddP was confirmed using the heterologous expression,and in situ transcription of the gene in scallop gill tissues was demonstrated using reverse-transcription PCR.Together,these results revealed a taxonomically and functionally unique symbiont,which represents the first-documented DMSP-metabolizing symbiont likely to play significant roles in coastal marine ecosystems.
Hongzhe LiJiazhi DingLongji ZhuFei Xu...
190-200页查看更多>>摘要：Application of agricultural waste such as rapeseed meal(RM)is regarded as a sustainable way to improve soil phosphorus(P)availability by direct nutrient supply and stimulation of native phosphate-solubilizing microorganisms(PSMs)in soils.However,ex-ploration of the in situ microbial P solubilizing function in soils remains a challenge.Here,by applying both phenotype-based single-cell Raman with D2O labeling(Raman-D2O)and genotype-based high-throughput chips targeting carbon,nitrogen and P(CNP)functional genes,the effect of RM application on microbial P solubilization in three typical farmland soils was investigated.The abundances of PSMs increased in two alkaline soils after RM application identified by single-cell Raman D2O.RM application reduced the diversity of bacterial communities and increased the abundance of a few bacteria with reported P solubilization function.Genotypic analysis indicated that RM addition generally increased the relative abundance of CNP functional genes.A correlation analysis of the abun-dance of active PSMs with the abundance of soil microbes or functional genes was carried out to decipher the linkage between the phenotype and genotype of PSMs.Myxococcota and C degradation genes were found to potentially contribute to the enhanced microbial P release following RM application.This work provides important new insights into the in situ function of soil PSMs.It will lead to better harnessing of agricultural waste to mobilize soil legacy P and mitigate the P crisis.
Zheng LiQing WangNa LvGuojin Xu...
201-208页查看更多>>摘要：Mammalian endogenous retroviruses(ERVs)are ancient retroviruses that have been integrated into genomes.ERVs were believed to be inactive until the discovery of ERV transcription in the mouse genome.However,the transcription level and function of ERV elements in mammalian genomes are not well understood.In this study,we performed the first genome-wide scanning of ERV loci in the American mink(Neogale vison)genome(NeoERV)followed by transcriptomic analysis to detect actively transcribed NeoERV elements.A total of 365,791 NeoERV loci were identified,and161,205(44％)of these loci were found to be actively transcribed based on transcriptomic data from three types of tissues(amygdala,trachea and lung).More than one third of the actively transcribed NeoERV loci were tissue-specific.Furthermore,some of the active loci were associated with host gene transcription,and the level of NeoERV transcription was positively correlated with that of host genes,specifically when active loci were located in overlapped gene regions.An in-depth analysis of the envelope protein coding env gene showed that,in general,its transcription level was higher than that of NeoERVs,which is believed to be associated with host immunity.
Pandeng WangShao-Peng LiXian YangXingfeng Si...
209-215页
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