Difference between revisions of "Part:BBa K3766012"
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<partinfo>BBa_K3766012 short</partinfo>
 
<partinfo>BBa_K3766012 short</partinfo>
  
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AmpR
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This part is AmpR, an ''E. coli'' gene coding for a β-lactamase enzyme. It is a derivative of the TEM-1 β-lactamase (Uniprot P62593) with two mutations V82I and V182A. In addition, compared to the sequence found in pSB1A2 from which it was derived by PCR amplification, a synonymous mutation S240 (TCC->TCG) and a non synonymous mutation were detected L223I (CTT->ATT) that did not affect the capacity of this enzyme to confer resistance to ampicillin when expressed in ''Escherichia coli''.
  
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a non synonymous mutation detected : L223I (CTT->ATT) that did not affect the capacity of this enzyme to confer resistance to Ampicillin when expressed in ''Escherichia coli''.
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===Usage and Biology===
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AmpR is a protein associated with the resistance mechanism against the large family of β-lactams, antibiotics which include the well known penicillin and ampicillin.
  
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a synonymous mutation S240 (TCC->TCG)
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β-Lactamases act by hydrolysing the β-lactam ring (Figure 1), thus inactivating the antibiotic.
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[[File: T--Evry_Paris-Saclay--beta-lactam_ring_hydrolysis.png|center|300px]]
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Figure 1. The mode of action of β-lactamases: hydrolysis of the β-lactam ring.
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Fortunately, among all the subgroups of β-lactams (table 1), some have less affinity with the β-lactamase(s) and overcome this resistance. For example, in monobactams, Aztreonam is known to have a bactericidal effect even on bacteria carrying the AmpR gene [1]. We confirmed this experimentally by testing the resistance of the bacteria carrying AmpR to different β-lactam antibiotics (Figure 2).
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{| class="wikitable"
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!colspan="9"|Table 1. β-lactam groups and sub-groups, classified based on their core ring structures.
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|-
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|penams
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|carbapenams   
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|clavams
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|penems
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|carbapenems
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|cephems
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|carbacephems
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|oxacephems
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|monobactams
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|-
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|[[File: T--Evry_Paris-Saclay--penam.png|center]]   
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|[[File: T--Evry_Paris-Saclay--carbapenam.png|center]]
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|[[File: T--Evry_Paris-Saclay--clavam.png|center]]
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|[[File: T--Evry_Paris-Saclay--penem.png|center]] 
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|[[File: T--Evry_Paris-Saclay--carbapenam.png|center]]
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|[[File: T--Evry_Paris-Saclay--cephem.png|center]]
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|[[File: T--Evry_Paris-Saclay--carbacephem.png|center]] 
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|[[File: T--Evry_Paris-Saclay--oxacephem.png|center]] 
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|[[File: T--Evry_Paris-Saclay--monobactam.png|center]]
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|}
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[File: T--Evry_Paris-Saclay--AmpR_Ampi-Azt-Cefo-Cepha-Meth.png|center|300px]]
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Figure 2. Pictures of ''E. coli'' NEB5ɑ cells carrying the AmpR resistance gene (this part) plated on different concentrations of β-lactam antibiotics.
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===References===
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[1] Cantu C, Huang W, Palzkill T. Selection and characterization of amino acid substitutions at residues 237-240 of TEM-1 beta-lactamase with altered substrate specificity for aztreonam and ceftazidime. The Journal of Biological Chemistry (1996) 271: 22538–22545.
  
  
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===Usage and Biology===
 
  
 
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Revision as of 18:30, 20 October 2021


AmpR

This part is AmpR, an E. coli gene coding for a β-lactamase enzyme. It is a derivative of the TEM-1 β-lactamase (Uniprot P62593) with two mutations V82I and V182A. In addition, compared to the sequence found in pSB1A2 from which it was derived by PCR amplification, a synonymous mutation S240 (TCC->TCG) and a non synonymous mutation were detected L223I (CTT->ATT) that did not affect the capacity of this enzyme to confer resistance to ampicillin when expressed in Escherichia coli.

Usage and Biology

AmpR is a protein associated with the resistance mechanism against the large family of β-lactams, antibiotics which include the well known penicillin and ampicillin.

β-Lactamases act by hydrolysing the β-lactam ring (Figure 1), thus inactivating the antibiotic.

T--Evry Paris-Saclay--beta-lactam ring hydrolysis.png

Figure 1. The mode of action of β-lactamases: hydrolysis of the β-lactam ring.

Fortunately, among all the subgroups of β-lactams (table 1), some have less affinity with the β-lactamase(s) and overcome this resistance. For example, in monobactams, Aztreonam is known to have a bactericidal effect even on bacteria carrying the AmpR gene [1]. We confirmed this experimentally by testing the resistance of the bacteria carrying AmpR to different β-lactam antibiotics (Figure 2).

Table 1. β-lactam groups and sub-groups, classified based on their core ring structures.
penams carbapenams clavams penems carbapenems cephems carbacephems oxacephems monobactams
T--Evry Paris-Saclay--penam.png
T--Evry Paris-Saclay--carbapenam.png
T--Evry Paris-Saclay--clavam.png
T--Evry Paris-Saclay--penem.png
T--Evry Paris-Saclay--carbapenam.png
T--Evry Paris-Saclay--cephem.png
T--Evry Paris-Saclay--carbacephem.png
T--Evry Paris-Saclay--oxacephem.png
T--Evry Paris-Saclay--monobactam.png


[File: T--Evry_Paris-Saclay--AmpR_Ampi-Azt-Cefo-Cepha-Meth.png|center|300px]]

Figure 2. Pictures of E. coli NEB5ɑ cells carrying the AmpR resistance gene (this part) plated on different concentrations of β-lactam antibiotics.

References

[1] Cantu C, Huang W, Palzkill T. Selection and characterization of amino acid substitutions at residues 237-240 of TEM-1 beta-lactamase with altered substrate specificity for aztreonam and ceftazidime. The Journal of Biological Chemistry (1996) 271: 22538–22545.


Sequence and Features


Assembly Compatibility:
  • 10
    COMPATIBLE WITH RFC[10]
  • 12
    COMPATIBLE WITH RFC[12]
  • 21
    COMPATIBLE WITH RFC[21]
  • 23
    COMPATIBLE WITH RFC[23]
  • 25
    COMPATIBLE WITH RFC[25]
  • 1000
    COMPATIBLE WITH RFC[1000]