9SRT: Mlc tetramer

Cryo-EM structure of the Mlc tetramer. Determined by electron microscopy at 2.74 Å resolution. Released 22 Jul 2026.

Method: Electron microscopy
Resolution: 2.74 Å
Organism: Escherichia coli
Chains: 4
Atoms: 11,752
Mol. weight: 199.87 kDa
Ligands: ZN
Released: 22 Jul 2026

Explore 9SRT in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9SRT contains 75 α-helices and 87 β-strands across 4 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 19 helices, 21 β-strands

Element	Residues	Length	Sheet
α-helix	13-28	16
β-strand	31	1	22
α-helix	33-40	8
α-helix	44-56	13
β-strand	60-61	2	23
β-strand	78	1	22
β-strand	79-80	2	23
β-strand	86-92	7	24
β-strand	96-103	8	24
β-strand	108-115	8	24
α-helix	124-138	15
α-helix	140-142	3
β-strand	146-152	7	24
β-strand	156-158	3	25
β-strand	163-166	4	25
β-strand	176	1	25
α-helix	178-186	9
β-strand	190-193	4	24
α-helix	195-206	12
β-strand	215-220	6	26
β-strand	224-230	7	26
β-strand	233-234	2	26
α-helix	245-247	3
β-strand	249	1	27
α-helix	255	1
β-strand	256	1	28
α-helix	257	1
β-strand	262	1	28
β-strand	264	1	27
α-helix	266-269	4
α-helix	271-283	13
α-helix	297-306	10
α-helix	309-333	25
β-strand	337-341	5	26
α-helix	343-347	5
α-helix	348-362	15
α-helix	365-368	4
β-strand	372-375	4	26
α-helix	387-395	9
α-helix	398-404	7

Chain B: 18 helices, 22 β-strands

Element	Residues	Length	Sheet
α-helix	10-28	19
β-strand	31	1	15
α-helix	33-40	8
α-helix	44-56	13
β-strand	60-61	2	16
β-strand	78	1	15
β-strand	79-80	2	16
β-strand	86-93	8	17
β-strand	96-103	8	17
β-strand	108-115	8	17
α-helix	124-136	13
β-strand	146-153	8	17
β-strand	156-158	3	18
β-strand	163-166	4	18
β-strand	176	1	18
α-helix	178-186	9
β-strand	190-194	5	17
α-helix	195-206	12
β-strand	215-220	6	19
β-strand	224-230	7	19
β-strand	233-234	2	19
β-strand	243	1	19
α-helix	245-247	3
β-strand	249	1	20
α-helix	255	1
β-strand	256	1	21
α-helix	257	1
β-strand	262	1	21
β-strand	264	1	20
α-helix	266-269	4
α-helix	271-282	12
α-helix	297-305	9
α-helix	309-333	25
β-strand	337-341	5	19
α-helix	343-347	5
α-helix	348-362	15
α-helix	365-368	4
β-strand	373-375	3	19
α-helix	386-395	10
α-helix	398-403	6

Chain C: 19 helices, 22 β-strands

Element	Residues	Length	Sheet
α-helix	13-28	16
β-strand	31	1	8
α-helix	33-40	8
α-helix	44-56	13
β-strand	60-61	2	9
β-strand	78	1	8
β-strand	79-80	2	9
β-strand	85-92	8	10
β-strand	96-103	8	10
β-strand	108-115	8	10
α-helix	124-138	15
α-helix	140-142	3
β-strand	145-153	9	10
β-strand	156-158	3	11
β-strand	163-166	4	11
β-strand	176	1	11
α-helix	178-186	9
β-strand	190-194	5	10
α-helix	195-206	12
β-strand	215-219	5	12
β-strand	225-230	6	12
β-strand	233-234	2	12
β-strand	243	1	12
α-helix	245-247	3
β-strand	249	1	13
α-helix	255	1
β-strand	256	1	14
α-helix	257	1
β-strand	262	1	14
β-strand	264	1	13
α-helix	266-269	4
α-helix	271-283	13
α-helix	297-306	10
α-helix	309-333	25
β-strand	337-341	5	12
α-helix	343-347	5
α-helix	348-362	15
α-helix	365-368	4
β-strand	372-375	4	12
α-helix	386-395	10
α-helix	398-404	7

Chain D: 19 helices, 22 β-strands

Element	Residues	Length	Sheet
α-helix	10-28	19
β-strand	31	1	1
α-helix	33-40	8
α-helix	44-56	13
β-strand	60-61	2	2
β-strand	78	1	1
β-strand	79-80	2	2
β-strand	86-93	8	3
β-strand	96-103	8	3
β-strand	108-115	8	3
α-helix	124-136	13
β-strand	146-153	8	3
β-strand	156-158	3	4
β-strand	163-166	4	4
β-strand	176	1	4
α-helix	178-186	9
β-strand	190-194	5	3
α-helix	195-206	12
β-strand	215-220	6	5
β-strand	224-230	7	5
β-strand	233-234	2	5
β-strand	243	1	5
α-helix	245-247	3
β-strand	249	1	6
α-helix	255	1
β-strand	256	1	7
α-helix	257	1
β-strand	262	1	7
β-strand	264	1	6
α-helix	266-269	4
α-helix	271-282	12
α-helix	297-305	9
α-helix	309-333	25
β-strand	337-341	5	5
α-helix	343-347	5
α-helix	348-362	15
α-helix	365-368	4
β-strand	373-375	3	5
α-helix	384-386	3
α-helix	387-395	9
α-helix	398-403	6

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
DNA-binding transcriptional repressor Mlc	A, B, C, D	protein	455	Escherichia coli	P50456 (AlphaFold model)

Sequence of entity 1 (A, B, C, D), FASTA

>9SRT_1 DNA-binding transcriptional repressor Mlc (chains A, B, C, D)
MGGSHHHHHHGMASMTGGQQMGRDLYDDDDKDRWGSELEVLFQGPKLMVAENQPGHIDQI
KQTNAGAVYRLIDQLGPVSRIDLSRLAQLAPASITKIVREMLEAHLVQELEIKEAGNRGR
PAVGLVVETEAWHYLSLRISRGEIFLALRDLSSKLVVEESQELALKDDLPLLDRIISHID
QFFIRHQKKLERLTSIAITLPGIIDTENGIVHRMPFYEDVKEMPLGEALEQHTGVPVYIQ
HDISAWTMAEALFGASRGARDVIQVVIDHNVGAGVITDGHLLHAGSSSLVEIGHTQVDPY
GKRCYCGNHGCLETIASVDSILELAQLRLNQSMSSMLHGQPLTVDSLCQAALRGDLLAKD
IITGVGAHVGRILAIMVNLFNPQKILIGSPLSKAADILFPVISDSIRQQALPAYSQHISV
ESTQFSNQGTMAGAALVKDAMYNGSLLIRLLQGLE

Ligands and cofactors

ID	Name	Formula	Copies
ZN	Zinc ion	Zn	4

Primary citation

Structural basis of Mlc-mediated transcriptional regulation of carbohydrate metabolism. Roth, P., Fender, I., Jeckelmann, J.M. et al. Nat Commun (2026) 17. DOI 10.1038/s41467-026-75270-8 · PubMed

Other PDB entries of the same protein (UniProt P50456 (AlphaFold model), which also has an AlphaFold model), best resolution first:

9SRW 2.3 Å, Cryo-EM structure of the Mlc tetramer in complex with the anti-repressor MtfA
9SRU 2.47 Å, Cryo-EM structure of Mlc in complex with ptsG operator DNA
1Z6R 2.7 Å, Crystal structure of Mlc from Escherichia coli
3BP8 2.85 Å, Crystal structure of Mlc/EIIB complex
9SRX 2.96 Å, Cryo-EM structure of the Mlc repressor in complex with the glucose-specific IICB…

Browse structure collections

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