monotrichous

Deep research

Generated by just research-trait; source: research/traits/morphology/monotrichous-deep-research-falcon.md

# Curation report: monotrichous (`traitmech:000057`)

## Executive summary

**Recommended scope.** The trait denotes the morphological state in which a bacterial cell bears **one flagellum at one cell pole**. A direct literature definition contrasts peritrichous *Salmonella/E. coli* with *Vibrio/Pseudomonas* cells possessing “a single flagellum at one of the cell poles (monotrichous flagellum).” The defining variables are therefore **number = 1**, **position = polar**, and presence of the assembled appendage—not swimming performance alone (terashima2020assemblymechanismof pages 2-4).

The strongest currently supported causal module is:

**FipA + HubP/FimV → polar recruitment/activation of FlhF → capture of polar-system FliG → recruitment and assembly of FliF into the MS-ring → progressive polar flagellum assembly**, opposed by **FlhG/FleN**, which stimulates FlhF GTPase activity and limits repeated initiation. The clearest direct molecular dissection was published in 2024 for *Shewanella putrefaciens*, while comparative 2024 work supports a conserved but quantitatively variable FipA–FlhF mechanism in *Vibrio parahaemolyticus*, *Pseudomonas putida*, and *S. putrefaciens* (arroyoperez2024aconservedcellpole pages 14-15, arroyoperez2024aconservedcellpole pages 2-3, dornes2024polarconfinementof pages 1-2).

| subject | predicate | object | organism scope | confidence |
|---|---|---|---|---|
| FipA | interacts with and promotes polar membrane recruitment of | FlhF | Polar-flagellated γ-proteobacteria studied: *Vibrio parahaemolyticus*, *Pseudomonas putida*, *Shewanella putrefaciens* (arroyoperez2024aconservedcellpole pages 1-2, arroyoperez2024aconservedcellpole pages 14-15, arroyoperez2024aconservedcellpole pages 2-3) | high |
| HubP/FimV | recruits or anchors at pole | FlhF | Strongest direct evidence in *S. putrefaciens*; cooperative role with FipA across *Vibrio/Pseudomonas/Shewanella* (arroyoperez2024aconservedcellpole pages 14-15, dornes2024polarconfinementof pages 4-6, dornes2024polarconfinementof pages 1-2) | high |
| FlhF | binds | FliG | Direct biochemical and Y2H evidence in *S. putrefaciens* polar flagellar system (dornes2024polarconfinementof pages 2-4, dornes2024polarconfinementof pages 1-2) | high |
| FlhF-bound FliG | captures | FliF | Direct mechanistic model and pulldown-supported interaction sequence in *S. putrefaciens*; supported by Vibrio MS-ring initiation studies (arroyoperez2024aconservedcellpole pages 2-3, dornes2024polarconfinementof pages 2-4, dornes2024polarconfinementof pages 4-6, dornes2024polarconfinementof pages 1-2) | high |
| FliF | assembles into | MS-ring | Strong direct evidence in *Vibrio*; general bacterial flagellar initiation step (terashima2020assemblymechanismof pages 1-2, terashima2020assemblymechanismof pages 4-6, dornes2024polarconfinementof pages 1-2) | high |
| FlhG | stimulates GTPase activity of | FlhF | Polar-flagellated bacteria; direct mechanistic statement and review-supported conserved role (arroyoperez2024aconservedcellpole pages 14-15, terashima2020assemblymechanismof pages 2-4, dornes2024polarconfinementof pages 1-2) | high |
| FlhG-stimulated FlhF inactivation | limits additional initiation of | polar flagellum assembly events | Best supported in *Vibrio* and *Shewanella*; conserved control of flagellar number/location (arroyoperez2024aconservedcellpole pages 2-3, arroyoperez2024aconservedcellpole pages 14-15, terashima2020assemblymechanismof pages 2-4, dornes2024polarconfinementof pages 1-2) | high |
| assembled polar flagellar motor and filament | realizes | traitmech:000057 | Monotrichous bacteria with one polar flagellum; trait outcome distinct from motility alone (arroyoperez2024aconservedcellpole pages 1-2, terashima2020assemblymechanismof pages 2-4, dornes2024polarconfinementof pages 1-2) | medium-high |


*Table: This table summarizes the highest-confidence mechanistic edges for a candidate monotrichous TraitMech graph. It condenses the core FlhF-FlhG-HubP/FimV-FipA-FliG-FliF pathway into curator-ready subject-predicate-object statements with organism scope and confidence.*

## 1. Trait scope and boundaries

### 1.1 Inclusion criteria

Curate `traitmech:000057` when an assay establishes:

1. one bacterial flagellum or flagellar filament per cell;
2. insertion at a pole, including an explicitly monopolar/old-pole position;
3. the mature morphological state, or a mechanism directly shown to generate that state.

A sheathed polar filament, as found in many *Vibrio* species, remains monotrichous if there is exactly one polar flagellum; sheath status is a separate structural attribute (arroyoperez2024aconservedcellpole pages 1-2).

### 1.2 Nearby traits that should remain separate

- **Lophotrichous:** multiple flagella forming a tuft at one pole. *P. putida* is treated as lophotrichous in the 2024 comparative study and should not be used as direct organism-level evidence for the terminal monotrichous phenotype, although it provides useful evidence for shared upstream machinery (arroyoperez2024aconservedcellpole pages 2-3).
- **Amphitrichous:** one or more flagella at both poles; number and bipolarity differ from the target state.
- **Peritrichous:** flagella distributed around the cell surface. The 2020 *Vibrio* study explicitly contrasts this state in *E. coli/Salmonella* with a single polar flagellum (terashima2020assemblymechanismof pages 2-4).
- **Lateral flagellation:** a separate flagellar system may coexist with the primary polar system. *S. putrefaciens* has a primary FlhF/FlhG-dependent polar system and a secondary FlhF/FlhG-independent lateral system; consequently, whole-cell “exactly one flagellum” must be established under the assayed condition rather than inferred solely from the polar module (dornes2024polarconfinementof pages 1-2).
- **Periplasmic/endoflagellar arrangements:** *Borrelia burgdorferi* bears 7–11 periplasmic flagella from each pole, not a single external polar flagellum. Its FlhF mechanism is evolutionarily informative but its phenotype is outside this trait (zhang2020flhfregulatesthe pages 1-2).
- **Motile/nonmotile:** motility is a physiological output influenced by motor energization, filament integrity, viscosity, and assay conditions. It is not equivalent to flagellar number or location. A mutant may retain polar flagella but swim poorly, or lose polar placement while retaining some motility.
- **Transient cell-cycle states:** newly divided cells may not yet have completed assembly. Curate the species/strain phenotype from an appropriate population and growth phase, not from an isolated preassembly cell.

### 1.3 Recommended graph interpretation

The terminal node should represent an **assay-observed morphology**, not a genomic capability. Presence of `flhF`, `flhG`, or `fipA` is insufficient because these genes also occur in organisms with lophotrichous or other polar patterns. The 2024 comparative genomic analysis found FipA only with FlhF/FlhG and in the sampled polar flagellates, but those species included both monotrichous and lophotrichous arrangements (arroyoperez2024aconservedcellpole pages 2-3).

## 2. Candidate nodes grouped by type

### 2.1 Trait and cellular structures

| Candidate node | Type | Suggested grounding | Curation note |
|---|---|---|---|
| monotrichous | morphology class | `traitmech:000057` | Quote identifier verbatim in YAML. |
| bacterial-type flagellum | cellular component | `GO:0009288` | Mature appendage; verify GO release during implementation. |
| bacterial flagellar basal body | cellular component | `GO:0009425` | Broad structural parent for motor base. |
| MS-ring | complex, label-first | GO lookup recommended | Built from multiple FliF copies in the cytoplasmic membrane. |

Showing the first 60 of 235 lines of findings; the linked file also carries the run's front matter and the prompt it was given — read the full report.