TABLE 2.

Intermolecular contacts in the HPr-HPrK/P complexa

HPr residuebInteraction visible in X-ray structureInteraction visible by NMRe
AtomcHPrK/P residuedAtomcHNCO15N HSQC1H NMR
Thr12(Ser)OIle301sc××
Gly13HαIle301sc××
Ile14××
His15HαLeu297sc××
HαIle301sc
scLeu297sc
scIle301sc
Ala16HNLeu297sc××
scAsn294(Glu)sc
Arg17××
Ala19×
Gln24×
Tyr37scAsn308sc×
Lys40scThr132(Arg)Hα
scThr132(Arg)C′
scThr132(Arg)O
scThr132(Arg)sc
scSer134sc
scAsn176(Arg)sc
Lys41(Thr)OSer134sc
Val42scAsn176(Arg)sc
Asn43scHis136sc
Lys45C′Ser153sc
OSer153sc
scSer153sc
Ser46scHis136sc×
scAsp175sc
Ile47scGlu200sc×
Met48HNAsp175sc×
OIle195(Leu)sc
scAsp175sc
scIle195(Leu)sc
scGlu200sc
Gly49HNAsp175sc
HαAsn176(Arg)sc
Val50×
Met51OLeu297sc×××
scPhe293sc
scLeu297sc
Ser52CαLeu194(Ile)sc×
HαLeu194(Ile)sc
OAsn176(Arg)sc
OLeu194(Ile)sc
OGlu300(Leu)sc
scAsn176(Arg)sc
scLeu194(Ile)sc
scIle195(Leu)sc
Leu53HαAsn176(Arg)sc×
Gly54CαIle301sc×
HαLeu297sc
HαGlu300(Leu)sc
HαIle301sc
HαAsn304sc
C′Ile301sc
C′Asn304sc
OIle301Hα
OIle301sc
OArg303(His)sc
OAsn304sc
Val55(Ile)NIle301sc×
C′Ile301sc
OIle301sc
Gly56(Ala)CαIle301sc×
Hα1Asn304sc
Hα1Ile301sc
scLeu297Hα
scIle301O
scIle305sc
scArg303(His)HN
scArg303(His)sc
scAsn304sc
scGly305(Glu)sc
Lys57OGly305(Glu)sc
scGly305(Glu)sc
Ser78(Glu)×
Leu81(Met)×
• a The X-ray structure of the complex of unphosphorylated HPr from B. subtilis with HPrK/P (1KKL.pdb) from L: casei (12) was used for the analysis. Hydrogen atoms were added with the program Molmol and intermolecular contacts were identified. Contacts were defined as having an interatomic distance of <0.29 nm.

• b Residue types and numbering are for HPr from S. aureus. The corresponding residues in HPr from B. subtilis are given in parentheses, and residues that are strictly conserved in all HPr proteins are given in bold. Compared to HPr from S. aureus, HPr from S. xylosus has five mutated residues, namely Asn4-Lys, Ser71-Thr, Gln75-Glu, Ser78-Thr, and Val80-Ile.

• c sc, side chain atoms.

• d Residue types and numbering are for HPrK/P from S. xylosus. Note that the alignment of the two sequences leads to a shift of four residues. For residues that are not conserved, the corresponding amino acid HPrK/P from L. casei is given in parentheses.

• e ×, an interaction was visible.