Arginine deiminase system facilitates environmental adaptability of Streptococcus equi ssp.zooepidemicus through pH adjustment
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- 英文论文题名：Arginine deiminase system facilitates environmental adaptability of Streptococcus equi ssp.zooepidemicus through pH adjustment
- 论文作者：Bin Xu ; Hongjie Fan
- 英文论文作者：Bin Xu ; Hongjie Fan ; College of Veterinary Medicine ; Nanjing Agricultural University
- 年：2016
- 作者机构：College of Veterinary Medicine,Nanjing Agricultural University;
- 会议召开时间：2016-07-20
- 会议录名称：中国畜牧兽医学会兽医公共卫生学分会第五次学术研讨会论文集
- 语种：英文
- 分类号：S852.611
- 学会代码：SYGW
- 会议名称：中国畜牧兽医学会兽医公共卫生学分会第五次学术研讨会
- 会议地点：中国内蒙古通辽
- 主办单位：中国畜牧兽医学会兽医公共卫生学分会
- 学会名称：中国畜牧兽医学会兽医公共卫生学分会
- 页数：2
- 文件大小：518k
- 原文格式：D
- 会议级别：全国
摘要
The arginine deiminase system(ADS) is a secondary metabolic system found in many different bacterial pathogens,and it is often associated with virulence.Here,a systematic study of ADS functions in Streptococcus equi subsp.zooepidemicus(SEZ) was performed.Transcriptional levels of ADS operon genes were observed to be significantly increased when SEZ was grown under acidic conditions.It is noteworthy that the degree of upregulation in m RNA levels was different in the polycistron of ADS,let alone the two monocistrons,arg R and flp S.Moreover,arc A,orf2,arc B,arc D,arc T,and arc C can be inferred to form three kinds of co-transcription mode.We constructed arc A and arc D deletion mutants(SEZ △arc A and SEZ △arc D,respectively).We found that the arginine metabolism,which produces ATP,led to enhanced growth of SEZ when the carbohydrate supply was insufficient,as the SEZ △arc A,which could barely metabolize arginine,was unable to proliferate to a great extent during 24 h of growth when compared with wild-type SEZ in the same culture medium.Without sufficient arginine or enzymatic activity of Arc A,the medium in which SEZ was grown would acidify to the same extent.Meanwhile,the mutant deleted arginine deiminase(Arc A) could hardly produce ammonia.In addition,in silico analysis of the complete genome of SEZ(CP002904.1) showed no urease-like gene,which exists in some oral bacteria such as Streptococcus salivarius and Actinomyces naeslundii.These results confirmed that only the consumption of arginine would result in the production of ammonia,which alkalized the environment,and this progress wasbasically began with the conversion of arginine to citrulline via the catalytic activity of Arc A.In striking contrast,the p H value of the medium supplemented with arginine in which SEZ △arc D was grown began to increase after 10 h of incubation,which was entirely different from that observed for the arc D-deleted mutant of S.suis;the p H value of the medium under the same conditions decreased during the entire24 h growth period,just similar to that of the medium under the same conditions in which the SEZ △arc A was grown.The differences of bacterial concentration as well as ammonia concentration and arginine contentin the culture medium in which bacteria was grown between SEZ △arc D and wild-type SEZ continued to reduce in long term bacteria cultivation(after 12 h).All results indicated that,except for Arc D,a putative arginine/ornithine antiporter,some other arginine uptake pathways exist and maintain the normal operation of ADS to some extent.The differences in phenotype of arc D-deleted mutant between SEZ and S.suis mentioned above make the SEZ become a better target to study other possible arginine uptake mechanism.In research about Streptococcus pneumoniae and Streptococcus agalactiae showed that many other genes are involved in arginine uptake,such as abp A,abp B,aap A,and art PQ genes which encode arginine uptake transporters;arginine biosynthetic genes arg GH;and theali B gene,which encodes an oligopeptide-binding protein that contributes to the uptake of arginine containing peptides.The SEZ contains no arg GH via in silico analysis.It is quite possible that the consumption of arginine in SEZ only depends on the arginine uptake from the environment.Therefore,we performed q PCR analyses of SEZ △arc D compared with wild-type SEZ grown in TY medium with galactose and arginine at a p H of 7.As a result,the deletion of arc D did not lead to the significantly upregulated expression of other genes that are related to uptake of amino acid or oligopeptide(some of them exhibit amino acid identity with genes involving in uptake of arginine or argininecontaining peptides in S.pneumonia mentioned above,Table S2),which indicates regulation of the expression of these genes is not affected by the decrease of the arginine uptake level,as well as the decrease of the arginine metabolism level.The identification of alternative arginine transport systems remains to be determined.
The arginine deiminase system(ADS) is a secondary metabolic system found in many different bacterial pathogens,and it is often associated with virulence.Here,a systematic study of ADS functions in Streptococcus equi subsp.zooepidemicus(SEZ) was performed.Transcriptional levels of ADS operon genes were observed to be significantly increased when SEZ was grown under acidic conditions.It is noteworthy that the degree of upregulation in m RNA levels was different in the polycistron of ADS,let alone the two monocistrons,arg R and flp S.Moreover,arc A,orf2,arc B,arc D,arc T,and arc C can be inferred to form three kinds of co-transcription mode.We constructed arc A and arc D deletion mutants(SEZ △arc A and SEZ △arc D,respectively).We found that the arginine metabolism,which produces ATP,led to enhanced growth of SEZ when the carbohydrate supply was insufficient,as the SEZ △arc A,which could barely metabolize arginine,was unable to proliferate to a great extent during 24 h of growth when compared with wild-type SEZ in the same culture medium.Without sufficient arginine or enzymatic activity of Arc A,the medium in which SEZ was grown would acidify to the same extent.Meanwhile,the mutant deleted arginine deiminase(Arc A) could hardly produce ammonia.In addition,in silico analysis of the complete genome of SEZ(CP002904.1) showed no urease-like gene,which exists in some oral bacteria such as Streptococcus salivarius and Actinomyces naeslundii.These results confirmed that only the consumption of arginine would result in the production of ammonia,which alkalized the environment,and this progress wasbasically began with the conversion of arginine to citrulline via the catalytic activity of Arc A.In striking contrast,the p H value of the medium supplemented with arginine in which SEZ △arc D was grown began to increase after 10 h of incubation,which was entirely different from that observed for the arc D-deleted mutant of S.suis;the p H value of the medium under the same conditions decreased during the entire24 h growth period,just similar to that of the medium under the same conditions in which the SEZ △arc A was grown.The differences of bacterial concentration as well as ammonia concentration and arginine contentin the culture medium in which bacteria was grown between SEZ △arc D and wild-type SEZ continued to reduce in long term bacteria cultivation(after 12 h).All results indicated that,except for Arc D,a putative arginine/ornithine antiporter,some other arginine uptake pathways exist and maintain the normal operation of ADS to some extent.The differences in phenotype of arc D-deleted mutant between SEZ and S.suis mentioned above make the SEZ become a better target to study other possible arginine uptake mechanism.In research about Streptococcus pneumoniae and Streptococcus agalactiae showed that many other genes are involved in arginine uptake,such as abp A,abp B,aap A,and art PQ genes which encode arginine uptake transporters;arginine biosynthetic genes arg GH;and theali B gene,which encodes an oligopeptide-binding protein that contributes to the uptake of arginine containing peptides.The SEZ contains no arg GH via in silico analysis.It is quite possible that the consumption of arginine in SEZ only depends on the arginine uptake from the environment.Therefore,we performed q PCR analyses of SEZ △arc D compared with wild-type SEZ grown in TY medium with galactose and arginine at a p H of 7.As a result,the deletion of arc D did not lead to the significantly upregulated expression of other genes that are related to uptake of amino acid or oligopeptide(some of them exhibit amino acid identity with genes involving in uptake of arginine or argininecontaining peptides in S.pneumonia mentioned above,Table S2),which indicates regulation of the expression of these genes is not affected by the decrease of the arginine uptake level,as well as the decrease of the arginine metabolism level.The identification of alternative arginine transport systems remains to be determined.
The arginine deiminase system(ADS) is a secondary metabolic system found in many different bacterial pathogens,and it is often associated with virulence.Here,a systematic study of ADS functions in Streptococcus equi subsp.zooepidemicus(SEZ) was performed.Transcriptional levels of ADS operon genes were observed to be significantly increased when SEZ was grown under acidic conditions.It is noteworthy that the degree of upregulation in m RNA levels was different in the polycistron of ADS,let alone the two monocistrons,arg R and flp S.Moreover,arc A,orf2,arc B,arc D,arc T,and arc C can be inferred to form three kinds of co-transcription mode.We constructed arc A and arc D deletion mutants(SEZ △arc A and SEZ △arc D,respectively).We found that the arginine metabolism,which produces ATP,led to enhanced growth of SEZ when the carbohydrate supply was insufficient,as the SEZ △arc A,which could barely metabolize arginine,was unable to proliferate to a great extent during 24 h of growth when compared with wild-type SEZ in the same culture medium.Without sufficient arginine or enzymatic activity of Arc A,the medium in which SEZ was grown would acidify to the same extent.Meanwhile,the mutant deleted arginine deiminase(Arc A) could hardly produce ammonia.In addition,in silico analysis of the complete genome of SEZ(CP002904.1) showed no urease-like gene,which exists in some oral bacteria such as Streptococcus salivarius and Actinomyces naeslundii.These results confirmed that only the consumption of arginine would result in the production of ammonia,which alkalized the environment,and this progress wasbasically began with the conversion of arginine to citrulline via the catalytic activity of Arc A.In striking contrast,the p H value of the medium supplemented with arginine in which SEZ △arc D was grown began to increase after 10 h of incubation,which was entirely different from that observed for the arc D-deleted mutant of S.suis;the p H value of the medium under the same conditions decreased during the entire24 h growth period,just similar to that of the medium under the same conditions in which the SEZ △arc A was grown.The differences of bacterial concentration as well as ammonia concentration and arginine contentin the culture medium in which bacteria was grown between SEZ △arc D and wild-type SEZ continued to reduce in long term bacteria cultivation(after 12 h).All results indicated that,except for Arc D,a putative arginine/ornithine antiporter,some other arginine uptake pathways exist and maintain the normal operation of ADS to some extent.The differences in phenotype of arc D-deleted mutant between SEZ and S.suis mentioned above make the SEZ become a better target to study other possible arginine uptake mechanism.In research about Streptococcus pneumoniae and Streptococcus agalactiae showed that many other genes are involved in arginine uptake,such as abp A,abp B,aap A,and art PQ genes which encode arginine uptake transporters;arginine biosynthetic genes arg GH;and theali B gene,which encodes an oligopeptide-binding protein that contributes to the uptake of arginine containing peptides.The SEZ contains no arg GH via in silico analysis.It is quite possible that the consumption of arginine in SEZ only depends on the arginine uptake from the environment.Therefore,we performed q PCR analyses of SEZ △arc D compared with wild-type SEZ grown in TY medium with galactose and arginine at a p H of 7.As a result,the deletion of arc D did not lead to the significantly upregulated expression of other genes that are related to uptake of amino acid or oligopeptide(some of them exhibit amino acid identity with genes involving in uptake of arginine or argininecontaining peptides in S.pneumonia mentioned above,Table S2),which indicates regulation of the expression of these genes is not affected by the decrease of the arginine uptake level,as well as the decrease of the arginine metabolism level.The identification of alternative arginine transport systems remains to be determined.
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