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A Mini-Review of Enteroaggregative Escherichia coli with a Specific Target on the Virulence Factors Controlled by the AggR Master Regulator

Jeannett Alejandra Izquierdo-Vega
Jeannett Alejandra Izquierdo-Vega
, 
Rubi Joseline Castillo-Juarez
Rubi Joseline Castillo-Juarez
, 
Manuel Sánchez-Gutiérrez
Manuel Sánchez-Gutiérrez
, 
Miguel A. Ares
Miguel A. Ares
 e 
Miguel A. De La Cruz
Miguel A. De La Cruz
   | 16 dic 2023
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Article Category: MINIREVIEW
Pubblicato online: 16 dic 2023
Pagine: 347 - 354
Ricevuto: 23 giu 2023
Accettato: 08 set 2023
DOI: https://doi.org/10.33073/pjm-2023-037
Parole chiave
© 2023 Jeannett Alejandra Izquierdo-Vega et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Fig. 1.

Schematic representation of EAEC virulence factors. Most EAEC virulence factors are regulated by the AggR transcriptional activator encoded on the plasmid of aggregative adherence (pAA). EAEC strains adhere in a “brick stacking” pattern and spread in intestinal epithelial cells via aggregative adherence fimbria (AAF). This AAF presents at least five antigenic variants regulated by the AggR master regulator. The AggR transcription factor also activates the genes that encode the anti-aggregation protein (Aap, dispersin) and its anti-aggregation transporter (Aat), and the type VI secretion system (T6SS). EAEC strains can form robust biofilms, which promote high resistance to desiccation, starvation, and host immune response. EAEC secretes at least three toxins: E. coli heat-stable enterotoxin (EAST-1), plasmid-encoded toxin, (Pet), and protein involved in colonization (Pic, with mucinase activity), which are not controlled by the AggR regulator, causing an increase in chloride secretion that correlates with secretory diarrhea.
Schematic representation of EAEC virulence factors. Most EAEC virulence factors are regulated by the AggR transcriptional activator encoded on the plasmid of aggregative adherence (pAA). EAEC strains adhere in a “brick stacking” pattern and spread in intestinal epithelial cells via aggregative adherence fimbria (AAF). This AAF presents at least five antigenic variants regulated by the AggR master regulator. The AggR transcription factor also activates the genes that encode the anti-aggregation protein (Aap, dispersin) and its anti-aggregation transporter (Aat), and the type VI secretion system (T6SS). EAEC strains can form robust biofilms, which promote high resistance to desiccation, starvation, and host immune response. EAEC secretes at least three toxins: E. coli heat-stable enterotoxin (EAST-1), plasmid-encoded toxin, (Pet), and protein involved in colonization (Pic, with mucinase activity), which are not controlled by the AggR regulator, causing an increase in chloride secretion that correlates with secretory diarrhea.

Fig. 2.

Regulatory model of AggR and Aar on the EAEC virulence genes. AggR master regulator activates the virulence regulon that includes: Aar regulatory protein, aggregative adherence fimbriae II (AAF/II), Type VI secretion system (T6SS), anti-aggregation protein (Aap, dispersin), and anti-aggregation transporter (Aat). Aar directly binds AggR, blocking its transcription activity. In addition, Aar forms multiprotein complexes together with H-NS, altering the repressor function of nucleoid protein on its promoter.
Regulatory model of AggR and Aar on the EAEC virulence genes. AggR master regulator activates the virulence regulon that includes: Aar regulatory protein, aggregative adherence fimbriae II (AAF/II), Type VI secretion system (T6SS), anti-aggregation protein (Aap, dispersin), and anti-aggregation transporter (Aat). Aar directly binds AggR, blocking its transcription activity. In addition, Aar forms multiprotein complexes together with H-NS, altering the repressor function of nucleoid protein on its promoter.

Virulence genes regulated by AggR*.

Location Virulence factor Regulated genes Description
pAA2 plasmid AAF/II aafA, aafB, aafC, aafD major subunit, minor subunit, usher protein, chaperone of AAF/II
dispersin aap dispersin (antiaggregation protein)
dispersin export apparatus aatA, aatB, aatC, aatD, aatP TolC-like outer membrane protein, hypothetic protein, ABC transporter, N-acyltransferase, permease protein
AggR aggR AraC/XylS-type transcriptional regulator
Aar aar ANR-family regulator
ORF3 EC042_RS26240 (pAA003) isoprenyl diphosphate synthase
Idi (ORF4) idi isopentenyl-diphosphate delta-isomerase
Shf shf polysaccharide deacetylase
EC042_RS30880 (pAA005A), EC042_RS26330 (pAA0020), (pAA0047), (pAA0056) hypothetical proteins
Chromosome Type VI secretion system aaiA-U (EC042_RS24360–EC042_RS24465) T6SS putative proteins
EC042_RS16995 (EC042_3181) putative transcriptional regulator
EC042_RS17000 (EC042_3182) ParB-type nuclease
EC042_RS17030 (EC042_3187) putative helicase
EC042_RS17005, EC042_RS17010, EC042_RS21290 (EC042_3183, EC042_3184, EC042_4006) hypothetic proteins
eISSN:
2544-4646
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Inglese
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Life Sciences, Microbiology and Virology
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