Part:BBa_I746000

AIP generator (agrB + agrD with RBSes)

This part was made in order to transfer the S. aureus oligopeptide-based quorum sensing system into a BioBrick-compatible signalling mechanism.

In the natural system, the signalling oligopeptide (termed AIP) is made from AgrD by the membrane-located enzyme AgrB. It is then detected by the membrane-located AgrC, which phosphorylates AgrA which then has DNA-binding activity and upregulates transcription of the promoters termed P2 and P3 in the agr locus. There are four known variants of AIP with different molecular structures and cross-inhibitory activity; this BioBrick generates group I AIP.

This part contains the coding regions for group I agrB and agrD (in that order) from S. aureus strain NCTC8325, prefixed by the B0034 RBS and separated by a SaII site.

Informational contributiontion by BNU-China 2021

Edited by Qiuchen Gu

Summmary

The autoinducing peptides(AIPs) has 4 types with different structures. AIP of one kind specifically activates corresponding AgrC receptor and meanwhile inhibits other types of AgrC receptors. The binding of AIP activates P2 and P3 promoters to regulate Staphylococcus aureus metabolism.

1. Different structures of AIP molecules

AgrD is transformed into mature autoinducing peptide(AIP) through the process of two protease cleavage and a thiolactone formation[1]. So far, four types of AIP have been found within Staphylococcus aureus (AIP I-IV) in different species[2]. AIPs have complicated relationship with different types of AgrC receptors. AIP of one kind specifically activates corresponding AgrC receptor and meanwhile inhibits other types of AgrC receptors[3].
Based on the sequence of the major amino acids of AIP, the Agr system of Staphylococcus aureus can be divided into four species, and Lyon et al. [2] found that AIP-I and AIP-IV differ in only one amino acid, and the aspartic acid at position 5 on AIP-I is a tyrosine in AIP-IV. However, unlike AIP-I, which strongly activates AgrC-I but largely fails to activate AgrC-IV, the AIP-IV strongly activates both AgrC-I and AgrC-IV. (Figure 1)

Figure 1 The structure of AIPs

2．How AIP inhibits/activates AgrC1.

AIP is a short peptide derived from AgrD, which is processed by AgrB to secrete AIP into the extracellular environment. The extracellular AIPs bind to transmembrane proteins AgrC, causing autophosphorylation of AgrC, which then transfers the phosphate to AgrA [1,2]. Phosphorylated AgrA activates the activity of P2 and P3 promoters[3,4], upregulating the expression of agrABCD and RNA III [3,4]. Figure 2 shows a schematic diagram of the entire system.

Figure 2 Schematic diagram of Agr two-component system

References

[1] Thoendel M, Horswill A R. Biosynthesis of peptide signals in gram-positive bacteria[J]. Advances in Applied Microbiology, 2010, 71(3):91-112.

[2] Lyon G J, Wright J S, Muir T W, et al. Key determinants of receptor activation in the agr autoinducing peptides of Staphylococcus aureus[J]. Biochemistry, 2002, 41: 10095－10104

[3] Novick R P, Projan S J, Kornblum J, et al. The agr P2 operon: an autocatalytic sensory transduction system in Staphylococcus aureus[J]Mol Gen Genet. 1995;248(4):446-458. doi:10.1007/BF02191645

[4] Koenig R L, Ray J L , Maleki S J , et al. Staphylococcus aureus AgrA Binding to the RNAIII-agr Regulatory Region[J]. Journal of Bacteriology, 2004, 186(22):7549-7555.

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]