3IOX

Crystal Structure of A3VP1 of AgI/II of Streptococcus mutans

Summary for 3IOX

• Entry DOI: 10.2210/pdb3iox/pdb
• Related: 1JMM 3IPK
• Descriptor: AgI/II, phenylmethanesulfonic acid, SULFITE ION, ... (5 entities in total)
• Functional Keywords: alpha helix, ppii helix, supersandwich fold, surface adhesin, cell wall, peptidoglycan-anchor, cell adhesion
• Biological source: Streptococcus mutans
• Total number of polymer chains: 1
• Total formula weight: 54824.73

Authors

Larson, M.R.,Rajashankar, K.R.,Patel, M.,Robinette, R.,Crowley, P.,Michalek, S.M.,Brady, L.J.,Deivanayagam, C.C. (deposition date: 2009-08-14, release date: 2010-04-14, Last modification date: 2023-09-06)

Primary citation

Larson, M.R.,Rajashankar, K.R.,Patel, M.H.,Robinette, R.A.,Crowley, P.J.,Michalek, S.,Brady, L.J.,Deivanayagam, C.
Elongated fibrillar structure of a streptococcal adhesin assembled by the high-affinity association of alpha- and PPII-helices.
Proc.Natl.Acad.Sci.USA, 107:5983-5988, 2010

PubMed Abstract: Streptococcus mutans antigen I/II (AgI/II) is a cell surface-localized protein adhesin that interacts with salivary components within the salivary pellicle. AgI/II contributes to virulence and has been studied as an immunological and structural target, but a fundamental understanding of its underlying architecture has been lacking. Here we report a high-resolution (1.8 A) crystal structure of the A(3)VP(1) fragment of S. mutans AgI/II that demonstrates a unique fibrillar form (155 A) through the interaction of two noncontiguous regions in the primary sequence. The A(3) repeat of the alanine-rich domain adopts an extended alpha-helix that intertwines with the P(1) repeat polyproline type II (PPII) helix to form a highly extended stalk-like structure heretofore unseen in prokaryotic or eukaryotic protein structures. Velocity sedimentation studies indicate that full-length AgI/II that contains three A/P repeats extends over 50 nanometers in length. Isothermal titration calorimetry revealed that the high-affinity association between the A(3) and P(1) helices is enthalpically driven. Two distinct binding sites on AgI/II to the host receptor salivary agglutinin (SAG) were identified by surface plasmon resonance (SPR). The current crystal structure reveals that AgI/II family proteins are extended fibrillar structures with the number of alanine- and proline-rich repeats determining their length.

PubMed: 20231452
DOI: 10.1073/pnas.0912293107

Experimental method

X-RAY DIFFRACTION (1.8 Å)