User:Fadel A. Samatey/FlgE I

Monomer Structures

Campylobacter jejuni

The structure of the flagellar hook monomer FlgE2 (gene Cj1729c) of Campylobacter jejuni () was determined to resolution 2.45 Å (5az4).

FlgE2 of C. jejuni (FlgE2-Cj; Q0P7Q2_CAMJE) consists of 865 amino acids. The fragment crystallized^[2] was residues 91-828 (738 residues, 85% of full length). The crystallographic model has coordinates for residues 94-819 (726 residues, 84% of full length). The 79 kD fragment crystallized will be referred to as FlgE2-Cj79.

FlgE2-Cj is composed of (D0-D4). D0 was not present in the fragment FlgE2-Cj79 in order to facilitate crystallization. D1-3 consist of discontinuous segments of the single protein chain, while D4 is one continuous segment. Here is a scene . The domains . D3 contains three alpha-helices while D4 contains one.

Caulobacter crescentus

The structure of the flagellar hook monomer FlgE (gene flgE) of Caulobacter cresentus Å (5ay6).

FlgE of C. crecentus (FlgE-Cc; P35806, FLGE_CAUCR, gene CC_0902) consists of 591 amino acids. The fragment crystallized was residues 165-470 (306 residues, 52% of full length). The crystallographic model has coordinates for residues 167-469 (303 residues, 51% of full length). The fragment crystallized is 32 kD, and will be referred to as FlgE-Cc32.

FlgE-Cc32 forms domains D2 and D3. D0 and D1 were removed to facilitate crystallization. D2 is formed by two discontinuous segments, while D3 is a single continuous segment inserted between the segments of D2. Here the model is .

Comparison with Salmonella

FlgE (gene STM1177) of Salmonella enterica serotype Typhimurium^[3] (FlgE-St, P0A1J1_SALTY) contains 403 amino acids, compared to the 865 in FlgE-Cj. However, the D1 and D2 domains are very similar in the two species (FlgE-St42: 1wlg).

FlgE-Cj contains the additional domains D3 and D4, making it a "hook with a hat".

A small adjustment in the angle between D1 and D2 in FlgE-Cj79 (a reduction of about 12^o) enables with FlgE-St42 (RMSD for 137 of 287 alpha carbons: 0.94 Å). The adjustment can also be .

There is also close structural similarity between domains D1 and D2 comparing FlgE-Cc32 with FlgE-St42, and comparing FlgE2-Cj79 with FlgE-Cc32 (Supplementary Fig. 3 in the journal article).

Caulobacter Hook Model

A model of the hook of Caulobacter crecentus was made by manually docking the crystallographic structure of FlgE-Cc32 domains D2 and D3 into the 20 Å electron density map published in 1981^[4]. Here you can (alpha carbons only, spacefilled to 3.5 Å^[5]).

Most of the large cavity is filled by domains D0 and D1, but these domains are missing in this model.

Each of the 11 protofilaments has a distinct color, so there are 11 colors. Here, . Each protofilament forms one of the 11-start helices.

There is a large space between domains D2+D3 within a protofilament. Thus, protofilaments are held together by interactions between D0 and D1 (missing in this model). However, domains D2+D3 interact between protofilaments, forming 6 helices. Here, .

• Black line: one of the 11-start protofilament helices.
• Red line: one of the 6-start helices.