Physical and genetic mapping of the Rhodobacter sphaeroides 2.4.1 genome: presence of two unique circular chromosomes
Physical and genetic mapping of the Rhodobacter sphaeroides 2.4.1 genome: presence of two unique circular chromosomes
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DOI：
10.1128/jb.171.11.5850-5859.1989
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发表时间：
1989-11
影响因子：
3.2
通讯作者：
A. Suwanto;S. Kaplan
中科院分区：
文献类型：
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作者：
A. Suwanto;S. Kaplan
通过对用限制性内切酶AseI、SpeI、DraI和SnaBI消化的总基因组DNA中的染色体DNA片段进行排序，构建了代表球形红细菌2.4.1染色体的完整物理图谱的宏观限制性内切酶图谱。来自野生型和各种突变株的染色体DNA的连接片段和多重限制性内切酶双酶切，结合Southern杂交分析，已被用于对所有染色体DNA片段进行排序。结果表明，R. sphaeroides 2.4.1携带两条不同的环状染色体，分别为3，046 +/- 95和914 +/- 17个碱基（kb）。染色体I（3，046 kb）和染色体II（914 kb）都含有rRNA顺反子。似乎只有一个拷贝的rRNA基因包含在染色体I（rrnA）和两个拷贝存在于染色体II（rrnB，rrnC）。此外，甘油醛3-磷酸脱氢酶（gapB）和δ-氨基乙酰丙酸合酶（hemT）的基因也存在于II号染色体上。在每种情况下，似乎都有第二个副本的每一个这些基因的染色体I，但DNA同源性的程度是非常低的。产生参与CO2固定的酶并与编码I型酶（即，I型区域）位于染色体I上，而代表II型区域的那些基因位于染色体II上。每个染色体的完整的物理和部分遗传图谱。
A macrorestriction map representing the complete physical map of the Rhodobacter sphaeroides 2.4.1 chromosomes has been constructed by ordering the chromosomal DNA fragments from total genomic DNA digested with the restriction endonucleases AseI, SpeI, DraI, and SnaBI. Junction fragments and multiple restriction endonuclease digestions of the chromosomal DNAs derived from wild-type and various mutant strains, in conjunction with Southern hybridization analysis, have been used to order all of the chromosomal DNA fragments. Our results indicate that R. sphaeroides 2.4.1 carries two different circular chromosomes of 3,046 +/- 95 and 914 +/- 17 kilobases (kb). Both chromosome I (3,046 kb) and chromosome II (914 kb) contain rRNA cistrons. It appears that only a single copy of the rRNA genes is contained on chromosome I (rrnA) and that two copies are present on chromosome II (rrnB, rrnC). Additionally, genes for glyceraldehyde 3-phosphate dehydrogenase (gapB) and delta-aminolevulinic acid synthase (hemT) are found on chromosome II. In each instance, there appears to be a second copy of each of these genes on chromosome I, but the extent of the DNA homology is very low. Genes giving rise to enzymes involved in CO2 fixation and linked to the gene encoding the form I enzyme (i.e., the form I region) are on chromosome I, whereas those genes representing the form II region are on chromosome II. The complete physical and partial genetic maps for each chromosome are presented.