Which genes does P. gingivalis need to grow?
A near-saturating Tn-seq screen finds ~463 (~22%) P. gingivalis genes putatively essential on blood agar.
Source
Identification of essential genes of the periodontal pathogen Porphyromonas gingivalis
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Which genes does P. gingivalis need to grow?
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463 (22.0%) genes putatively essential for in vitro survival.
Applying these rules, out of a total 2,102 genes in the ATCC 33277 genome (all protein coding sequences and rRNA genes combined minus the 53 tRNAs), we identified 463 (22.0%) genes as putatively essential for in vitro survival (described below) (Figure ) (Additional file : Table S1).
78.6% of putative essentials have known essential homologues.
gingivalis , 364 (78.6%) have known essential gene homologues determined by BLASTP interrogation of the DEG ( http://tubic.tju.edu.cn/deg/ ), version 6.8, updated on November 4, 2011 (Additional file : Table S1) [,].
What they did
Authors built a Mariner Tn-seq library in P. gingivalis ATCC 33277 and scored insertion under-representation to call genes required for in vitro survival on blood agar.
What they found
463 genes (22%) are putatively essential; most have essential homologues elsewhere, while ~21% may be species/niche-specific essentials.
The limits
What it doesn't show
Blood-agar essentials ≠ all virulence genes in the host; different selective pressures will reveal other gene sets.
Key terms
- Tn-seq
- Transposon insertion sequencing to find essential/conditioned genes.
- Essential gene
- Gene required for growth under the tested condition.
- Porphyromonas gingivalis
- Oral anaerobic keystone pathogen linked to periodontitis.
- Mariner transposon
- Mobile element inserting primarily at TA dinucleotides.
- Keystone pathogen
- Microbe whose presence disproportionately reshapes community and disease.
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Putative essential gene count:
Common questions
How many essentials were called?
463 genes (~22%).
What growth condition?
In vitro survival/growth on blood agar.
What method?
Mariner Tn-seq with quantitative sequencing.
Are all essentials universal?
No—about 21% lack DEG homologues and may be niche-specific.
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