CLAIMS
1. A method for producing a heterologous protein
comprising:
culturing a coryneform bacterium having a genetic construct for secretory expression of the heterologous protein; and
collecting the heterologous protein produced by secretory production,
wherein the coryneform bacterium has been modified so as to harbor a phoS gene encoding a mutant PhoS protein,
wherein the mutant PhoS protein is a PhoS protein having a mutation that improves the secretory production amount of the heterologous protein,
wherein the genetic construct comprises, in the direction from 5' to 3', a promoter sequence that functions in the coryneform bacterium, a nucleic acid sequence encoding a signal peptide that functions in the coryneform bacterium, and a nucleic acid sequence encoding the heterologous protein, and
wherein the heterologous protein is expressed as a fusion protein with the signal peptide.
2. The method according to Claim 1, wherein the mutation is a mutation of replacing an amino acid residue other than a histidine residue that is autophosphorylated with another amino acid residue in a wild-type PhoS protein.
3. The method according to Claim 1, wherein the mutation is a mutation of replacing an amino acid residue in a HisKA domain other than a histidine residue that is autophosphorylated with another amino acid residue in a wild-type PhoS protein.

4. The method according to Claim 1, wherein the mutation is a mutation of replacing an amino acid residue corresponding to the tryptophan residue at position 302 in SEQ ID NO: 4 with an amino acid residue other than aromatic amino acid and histidine residues in a wild-type PhoS protein.
5. A method for producing a heterologous protein comprising:
culturing a coryneform bacterium having a genetic construct for secretory expression of the heterologous protein; and
collecting the heterologous protein produced by secretory production,
wherein the coryneform bacterium has been modified so as to harbor a phoS gene encoding a mutant PhoS protein,
wherein the mutant PhoS protein is a PhoS protein having a mutation of replacing an amino acid residue corresponding to the tryptophan residue at position 302 in SEQ ID NO: 4 with an amino acid residue other than aromatic amino acid and histidine residues in a wild-type PhoS protein,
wherein the genetic construct comprises, in the direction from 5' to 3', a promoter sequence that functions in the coryneform bacterium, a nucleic acid sequence encoding a signal peptide that functions in the coryneform bacterium, and a nucleic acid sequence encoding the heterologous protein, and
wherein the heterologous protein is expressed as a fusion protein with the signal peptide.

6. The method according to Claim 4 or 5, wherein the amino acid residue other than aromatic amino acid and histidine residues is a lysine residue, alanine residue, valine residue, serine residue, cysteine residue, methionine residue, aspartic acid residue, or asparagine residue.
7. The method according to any one of Claims 2 to 6, wherein the wild-type PhoS protein is a protein defined in
(a), (b), or (c) mentioned below:
(a) a protein comprising the amino acid sequence of SEQ ID NO: 4, 54, 55, 56, 57, or 58;
(b) a protein comprising the amino acid sequence of SEQ ID NO: 4, 54, 55, 56, 57, or 58, but which includes substitution, deletion, insertion, or addition of 1 to 10 amino acid residues;
(c) a protein comprising an amino acid sequence showing an identity of 90% or higher to the amino acid sequence of SEQ ID NO: 4, 54, 55, 56, 57, or 58.

8. The method according to any one of Claims 1 to 7, wherein the signal peptide is a Tat-dependent signal peptide.
9. The method according to Claim 8, wherein the Tat-dependent signal peptide is selected from the group consisting of a TorA signal peptide, Sufi signal peptide, PhoD signal peptide, LipA signal peptide, and IMD signal peptide.
10. The method according to Claim 8 or 9, wherein the coryneform bacterium has further been modified so that the expression of one or more genes selected from genes

encoding a Tat secretion system is increased.
11. The method according to Claim 10, wherein the genes encoding a Tat secretion system consists of a tatA gene, tatB gene, tatC gene, and tatE gene.
12. The method according to any one of Claims 1 to 7, wherein the signal peptide is a Sec-dependent signal peptide.
13. The method according to Claim 12, wherein the Sec-dependent signal peptide is selected from the group consisting of a PS1 signal peptide, PS2 signal peptide, and SlpA signal peptide.
14. The method according to any one of Claims 1 to 13, wherein the genetic construct further comprises a nucleic acid sequence encoding an amino acid sequence comprising Gln-Glu-Thr between the nucleic acid sequence encoding the signal peptide that functions in the coryneform bacterium and the nucleic acid sequence encoding the heterologous protein.
15. The method according to Claim 14, wherein the genetic construct further comprises a nucleic acid sequence encoding an amino acid sequence used for enzymatic digestion between the nucleic acid sequence encoding the amino acid sequence comprising Gln-Glu-Thr and the nucleic acid sequence encoding the heterologous protein.
16. The method according to any one of Claims 1 to 15, wherein the coryneform bacterium is a bacterium belonging to the genus Corynebacterium.

17. The method according to Claim 16, wherein the coryneform bacterium is Corynebacterium glutamicum.
18. The method according to Claim 17, wherein the coryneform bacterium is a modified strain derived from Corynebacterium glutamicum AJ12036 (FERM BP-734) or from Corynebacterium glutamicum ATCC13869.
19. The method according to any one of Claims 1 to 18, wherein the coryneform bacterium is a coryneform bacterium of which the activity of a cell surface layer protein is reduced.
20. A coryneform bacterium,
which has been modified so as to harbor a phoS gene encoding a mutant PhoS protein,
wherein the mutant PhoS protein is a PhoS protein having a mutation of replacing an amino acid residue corresponding to the tryptophan residue at position 302 in SEQ ID NO: 4 with an amino acid residue other than aromatic amino acid and histidine residues in a wild-type PhoS protein.
21. The coryneform bacterium according to Claim 20, wherein the amino acid residue other than aromatic amino acid and histidine residues is a lysine residue, alanine residue, valine residue, serine residue, cysteine residue, methionine residue, aspartic acid residue, or asparagine residue.
22. The coryneform bacterium according to Claim 20 or 21, wherein the wild-type PhoS protein is a protein defined in

(a), (b), or (c) mentioned below:
(a) a protein comprising the amino acid sequence of SEQ ID NO: 4, 54, 55, 56, 57, or 58;
(b) a protein comprising the amino acid sequence of SEQ ID NO: 4, 54, 55, 56, 57, or 58, but which includes substitution, deletion, insertion, or addition of 1 to 10 amino acid residues;
(c) a protein comprising an amino acid sequence showing an identity of 90% or higher to the amino acid sequence of SEQ ID NO: 4, 54, 55, 56, 57, or 58.

23. The coryneform bacterium according to any one of Claims 20 to 22, wherein the coryneform bacterium is a bacterium belonging to the genus Corynebacterium.
24. The coryneform bacterium according to Claim 23, wherein the coryneform bacterium is Corynebacterium glut ami cum.
25. The coryneform bacterium according to Claim 24, wherein the coryneform bacterium is a modified strain derived from Corynebacterium glutamicum AJ12036 (FERM BP-734) or from Corynebacterium glutamicum ATCC13869.
26. The coryneform bacterium according to any one of Claims 20 to 25, wherein the coryneform bacterium is a coryneform bacterium of which the activity of a cell surface layer protein is reduced.