topA

168

DNA topoisomerase I

locus: BSU_16120

Molecular weight: 78.89 kDa

pI: 9.02

Protein length: 691 aa

Gene length: 2076 bp

function: relaxation of negatively supercoiled DNA behind RNA polymerase

product: DNA topoisomerase I

essential: quasi

ec: 5.99.1.2

synonyms: topA, topI

List of homologs in different organisms, belongs to COG0551 (Galperin et al., 2021)

Gene

Coordinates: 1,683,661  1,685,736

Phenotypes of a mutant

• the mutant tends to acquire suppressor mutations that result in improved growth [Pubmed|28189581]
• essential [Pubmed|25092907]
• non-essential according to [Pubmed|28189581], but only one resistance cassette was possible
• quasi-essential, deletion of [gene|41199C76DF8CA804B7B8878D61228B9542A96AE4|topA] results in the immediate acquisition of suppressor mutations that result in overexpression of [protein|1901C52DCB24B3D53150F6926C14907AC1B75293|parE]-[protein|9075DD0CC0B8554F0379732453665F43C70EFC26|parC] [pubmed|30957856]

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The protein

Catalyzed reaction/ biological activity

• relaxation of negatively supercoiled DNA
• ATP-independent breakage of single-stranded DNA, followed by passage and rejoining (according to UniProt)

Protein family

• Type IA topoisomerase family (together with [protein|7D5327BD1DD5FD5F90B2C849589923AA3D8B20EF|topB])(according to UniProt)

[wiki|Domains]

• N-terminal [wiki|TOPRIM domain] (aa 3-114) [Pubmed|9722641]

Structure

• [PDB|4RUL] (from ''E. coli'', 40% identity) [Pubmed|26490962]
• [AF|P39814]

Paralogous protein(s)

• [protein|7D5327BD1DD5FD5F90B2C849589923AA3D8B20EF|topB]

Biological materials

Mutant

• BKK16120 (Δ[gene|41199C76DF8CA804B7B8878D61228B9542A96AE4|topA]::kan  trpC2) available at [http://bgsc.org/getdetail.php?bgscid=BKK16120 BGSC],  [Pubmed|28189581], upstream reverse: _UP1_CATTTTCATCCCCCTCAAGA,  downstream forward: _UP4_TAGCGGTGAGCAGGGTCTTG
• GP1963 (Δ[gene|41199C76DF8CA804B7B8878D61228B9542A96AE4|topA]::aphA3 (citB-alsT)₁₆) [pubmed|30957856]

Expression vectors

• pGP2060: IPTG inducible expression, purification in ''E. coli'' with N-terminal Strep-tag, in [wiki|pGP172], available in [wiki|Jörg Stülke]'s lab

References

Reviews

• 25092907,6305585,16936698,29177730,33480441

Original Publications

• 17114254,16600296,27378778,9722641,28189581,28414321,21710567,29242163,26490962,25232096,23514156,22923519,10713132,12167668,30222737,30957856,30478267,32232337