Detection of hssS, hssR, hrtA, and hrtB genes and their expression by hemin in  Staphylococcus epidermidis.
Staphylococcus aureus  employs a heme sensing system (HssR-HssS) and a heme-regulated transporter efflux pump (HrtA-HrtB) to avoid the accumulation of heme, which is toxic at high concentrations. The detoxification system to heme has not been studied in  Staphylococcus epidermidis . In this work, the hssR, hssS, hrtA, and hrtB genes were detected, and their expression when stimulated by hemin in S. epidermidis was explored. In silico genomic analyses exhibited that the genetic organization of the hssRS and hrtAB genes was identical in 11 Staphylococcus species analyzed, including S. epidermidis. Slight variations were found in their syntenic regions. The predicted secondary structure of HrtAB proteins from these species was almost identical to these of S. aureus. Additionally, hrtAB promoter sequences of some species were analyzed, and 1 or 2 different nucleotide substitutions were found in the downstream motif. Concentrations of hemin above 5 µmol/L inhibited S. epidermidis growth. However, S. epidermidis that was pre-exposed to a subinhibitory hemin concentration (1 µmol/L) was able to grow when inoculated into medium containing above 5 µmol/L hemin. The expression levels of hrtA and hrtB genes in S. epidermidis exhibited a significant difference when they were stimulated with hemin. Our results suggest that the HrtAB could be involved in hemin detoxification of S. epidermidis.
Microbiology Department, Escuela Nacional de Ciencias Biológicas-IPN, Mexico City, Mexico.
Marco A
MA
Juárez-Verdayes
Pilar M
PM
González-Uribe
Humberto
H
Peralta
Sandra
S
Rodríguez-Martínez
Janet
J
Jan-Roblero
Rosalba
R
Escamilla-Hernández
Mario E
ME
Cancino-Diaz
Juan C
JC
Cancino-Diaz
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001665:Binding Sites; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D023061:Gene Order; D006427:Hemin / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D011401:Promoter Regions, Genetic / Q000235:genetics; D013211:Staphylococcus aureus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013212:Staphylococcus epidermidis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*
D001426:Bacterial Proteins; D006427:Hemin