Influence of Origin Recognition Complex Proteins on the Copy Numbers of Three Chromosomes in Haloferax volcanii
Influence of Origin Recognition Complex Proteins on the Copy Numbers of Three Chromosomes in Haloferax volcanii
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DOI：
10.1128/jb.00161-18
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发表时间：
2018-06
影响因子：
3.2
通讯作者：
Katharina Ludt;J. Soppa
中科院分区：
文献类型：
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作者：
Katharina Ludt;J. Soppa
古生菌的核心起源是由一个重复区域和一个与真核生物ORC蛋白同源的起源识别复合体(ORC)蛋白的相邻基因组成的。Haloferax Volcanii是个例外，因为它包含三条染色体上的六个复制起点，以及另外10个与起点不相邻的兽人基因。这个独特的ORC蛋白谱系被用来揭示核心起源的orc基因和起源-远程的orc基因的重要性。值得注意的是，所有ORC蛋白都影响至少一条染色体的拷贝数。其中一些影响了所有三条染色体的基因，表明反式调节在HFX中存在。火山二号。此外，还对古细菌ORC蛋白家族的进化进行了分析。摘要古生菌的复制起始涉及一种名为ORC、CDC6或ORc1/CDC6的蛋白质，它与真核起源识别复合体(ORC)蛋白和真核生物CDC6同源。古生物复制起始区由起源重复区域和相邻的orc基因组成。一些古菌只有一个复制起点和一个兽人基因，而另一些古菌则有多个。Haloferax Volcanii是一个例外，因为它总共包含三条染色体上的六个复制起点和16个orc基因。构建的系统发育树表明，orc基因的复制发生在进化过程中非常不同的时间。为了揭示ORC蛋白对染色体拷贝数和细胞适合性的影响，我们试图产生所有16个基因的缺失突变体。共产生12个单基因缺失突变体，其中只有3个orc基因是必需的。对于一个基因，缺失分析失败了。生长分析表明，没有缺失突变体存在生长缺陷，但与野生型相比，一些突变体具有轻微的生长优势。对缺失突变体的染色体拷贝数进行量化分析表明，所有12个ORC蛋白都影响一条、两条或全部三条染色体的拷贝数。ORC的缺失导致染色体拷贝数的增加或减少。因此，HFX中的染色体拷贝数。VolcanII由一个错综复杂的ORC蛋白网络调控。这与其他古生菌不同，在其他古生菌中，ORC蛋白通常特定地结合到邻近的起源。重要性古菌的核心起源由一个重复区域和一个邻近的起源识别复合体(ORC)蛋白的基因组成，该蛋白与真核ORC蛋白同源。Haloferax Volcanii是个例外，因为它包含三条染色体上的六个复制起点，以及另外10个与起点不相邻的兽人基因。这个独特的ORC蛋白谱系被用来揭示核心起源的orc基因和起源-远程的orc基因的重要性。值得注意的是，所有ORC蛋白都影响至少一条染色体的拷贝数。其中一些影响了所有三条染色体的基因，表明反式调节在HFX中存在。火山二号。此外，还对古细菌ORC蛋白家族的进化进行了分析。
The core origins of archaea are comprised of a repeat region and an adjacent gene for an origin recognition complex (ORC) protein, which is homologous to eukaryotic ORC proteins. Haloferax volcanii is exceptional because it contains six replication origins on three chromosomes and an additional 10 orc genes that are not adjacent to an origin. This unique ORC protein repertoire was used to unravel the importance of core origin orc genes and of origin-remote orc genes. Remarkably, all ORC proteins influenced the copy number of at least one chromosome. Some of them influenced those of all three chromosomes, showing that cross-regulation in trans exists in Hfx. volcanii. Furthermore, the evolution of the archaeal ORC protein family was analyzed. ABSTRACT Replication initiation in archaea involves a protein named ORC, Cdc6, or ORC1/Cdc6, which is homologous to the eukaryotic origin recognition complex (ORC) proteins and to the eukaryotic Cdc6. Archaeal replication origins are comprised of origin repeat regions and adjacent orc genes. Some archaea contain a single replication origin and a single orc gene, while others have more than one of each. Haloferax volcanii is exceptional because it contains, in total, six replication origins on three chromosomes and 16 orc genes. Phylogenetic trees were constructed that showed that orc gene duplications occurred at very different times in evolution. To unravel the influence of the ORC proteins on chromosome copy number and cellular fitness, it was attempted to generate deletion mutants of all 16 genes. A total of 12 single-gene deletion mutants could be generated, and only three orc gene turned out to be essential. For one gene, the deletion analysis failed. Growth analyses revealed that no deletion mutant had a growth defect, but some had a slight growth advantage compared to the wild type. Quantification of the chromosome copy numbers in the deletion mutants showed that all 12 ORC proteins influenced the copy numbers of one, two, or all three chromosomes. The lack of an ORC led to an increase or decrease of chromosome copy number. Therefore, chromosome copy numbers in Hfx. volcanii are regulated by an intricate network of ORC proteins. This is in contrast to other archaea, in which ORC proteins typically bind specifically to the adjacent origin. IMPORTANCE The core origins of archaea are comprised of a repeat region and an adjacent gene for an origin recognition complex (ORC) protein, which is homologous to eukaryotic ORC proteins. Haloferax volcanii is exceptional because it contains six replication origins on three chromosomes and an additional 10 orc genes that are not adjacent to an origin. This unique ORC protein repertoire was used to unravel the importance of core origin orc genes and of origin-remote orc genes. Remarkably, all ORC proteins influenced the copy number of at least one chromosome. Some of them influenced those of all three chromosomes, showing that cross-regulation in trans exists in Hfx. volcanii. Furthermore, the evolution of the archaeal ORC protein family was analyzed.